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Erza
a) \(\frac{3}{5}-\frac{1}{3}-\frac{1}{6}=\frac{18}{30}-\frac{10}{30}-\frac{5}{30}=\frac{18-10-5}{30}=\frac{1}{10}\)
b) \(\frac{4}{7}\times\frac{5}{8}\times\frac{7}{12}=\frac{4\times5\times7}{7\times8\times12}=\frac{140}{672}=\frac{5}{24}\)
c) \(\frac{25}{28}\div\frac{15}{14}\times\frac{6}{7}=\frac{25}{28}\times\frac{14}{15}\times\frac{6}{7}=\frac{25\times14\times6}{28\times15\times7}=\frac{2100}{2940}=\frac{5}{7}\)
Thấy đúg thì tk nha các bn !!
a,3/5 - 1/3 - 1/6
= 4/9 - 1/6
= 5/9
b,4/7x5/8x7/12
= 5/14 x 7/12
= 5/24
c,25/18 :15/14 x 6/7
= 25/28 x 14/15 x 6/7
= 5/6 x 6/7
= 5/7

\(30\%\cdot25\%-40\%+15\%\)
\(=\frac{3}{10}\cdot\frac{1}{4}-\frac{2}{5}+\frac{3}{20}\)
\(=\frac{3}{40}-\frac{2}{5}+\frac{3}{20}\)
\(=-\frac{7}{40}\)
Mình không biết sao nhưng ra số âm đấy bạn :v


a) \(\left(15-x\right)+\left(x-12\right)=7-\left(-8+x\right)\)
\(15-x+x-12=7+8-x\)
\(x=12\)
b) \(x-\left\{55-\left[49+\left(-28-x\right)\right]\right\}=13-\left\{47+\left[25-\left(32-x\right)\right]\right\}\)
\(x-55+49-28-x=13-47-25+32-x\)
\(x=7\)
\(a,\left(15-x\right)+\left(x-12\right)=7-\left(-8+x\right)\)
\(15-x+x-12=7+8-x\)
\(15-x=3\)
\(x=12\)
\(b,x-\left\{55-\left[49+\left(-28-x\right)\right]\right\}=13-\left\{47+\left[25-\left(32-x\right)\right]\right\}\)
\(x-\left[55-\left(49-28-x\right)\right]=13-\left[47+\left(25-32+x\right)\right]\)
\(x-\left(55-49+28+x\right)=13-\left(47+25-32+x\right)\)
\(x-\left(34+x\right)=13-\left(40+x\right)\)
\(x-34-x=13-40-x\)
\(-27-x=-34\)
\(x=-27--34\)
\(x=7\)
\(c,\left|x-10\right|-\left|-12\right|=4\)
\(\left|x-10\right|-12=4\)
\(\left|x-10\right|=16\)
\(\Rightarrow x-10=16\)hoặc \(x-10=-16\)
\(x=26\)hoặc \(x=-6\)

\(\left(24\%+\frac{3}{4}+0,76+25\%\right)\times\left(3\frac{5}{7}+1\frac{8}{28}\right)\)
\(=\left(\frac{6}{25}+\frac{3}{4}+0,76+\frac{1}{4}\right)\times\left(\frac{26}{7}+\frac{36}{28}\right)\)
\(=\left(\frac{6}{25}+1+0,76\right)\times\left(\frac{26}{7}+\frac{36}{28}\right)\)
\(=\left(\frac{6}{25}+1,76\right)\times\left(\frac{26}{7}+\frac{9}{7}\right)\)
\(=5\times\left(\frac{6}{25}+1,76\right)\)
= 5 x 2
= 10

\(\frac{1}{10}+\frac{4}{20}+\frac{9}{30}+\frac{4}{16}+\frac{25}{50}+\frac{36}{60}-x=2\)
\(\frac{1}{10}+\frac{1}{5}+\frac{3}{10}+\frac{1}{4}+\frac{1}{2}+\frac{3}{5}-x=2\)
\(\left(\frac{1}{10}+\frac{1}{5}+\frac{3}{10}+\frac{1}{4}+\frac{1}{2}+\frac{3}{5}\right)-x=2\)
\(\frac{39}{20}-x=2\)
\(x=\frac{39}{20}-2\)
\(x=\frac{-1}{20}\)
101+204+309+164+5025+6036−x=2
\(\frac{1}{10} + \frac{1}{5} + \frac{3}{10} + \frac{1}{4} + \frac{1}{2} + \frac{3}{5} - x = 2\)
\(\left(\right. \frac{1}{10} + \frac{1}{5} + \frac{3}{10} + \frac{1}{4} + \frac{1}{2} + \frac{3}{5} \left.\right) - x = 2\)
\(\frac{39}{20} - x = 2\)
\(x = \frac{39}{20} - 2\)
\(x = \frac{- 1}{20}\)


a. 420 : (x : 39) = 105
x : 39 = 420 : 105
x : 39 = 4
x = 4 x 39
x = 156
b. 200 - 18 : (372 : 3 : x - 1) - 28 = 166
200 - 28 - 166 = 18 : (372 : 3 : x - 1)
6 = 18 : (124 : x - 1)
18 : (124 : x - 1) = 6
124 : x - 1 = 18 : 6
124 : x - 1 = 3
124 : x = 4
x = 124 : 4
x = 31
c. 429 : (x + 31) = 11
x + 31 = 429 : 11
x + 31 = 39
x = 39 - 31
x = 8
d. 1615 : (X x 19) = 17
X x 19 = 1615 : 17
X x 19 = 95
X = 95 : 19
X = 5
cho mình xin tick nhé !
a: 420:(x:39)=105
=>\(x:39=420:105=4\)
=>\(x=4\times39=156\)
b: \(200-18:\left(372:3:x-1\right)-28=166\)
=>\(172-18:\left(124:x-1\right)=166\)
=>\(18:\left(124:x-1\right)=172-166=6\)
=>\(124:x-1=18:6=3\)
=>\(124:x=3+1=4\)
=>\(x=\frac{124}{4}=31\)
c: \(429:\left(x+31\right)=11\)
=>x+31=429:11=39
=>x=39-31=8
d: \(1615:\left(x\times19\right)=17\)
=>\(x\times19=1615:17=95\)
=>x=95:19=5
40 x 25 x 28
= 1000 x 28
= 28000
28000