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1)300:x-20:x=280:4
300:x-20:x=70
(300-20):x=70
280:x=70
x=280:70
x=4
2)x-63.11=156.420
x-693=65520
x =65520+693
x =66213
15,6 x 260 - 156 x 26=0
15,6 x 3,3 x 3,4 x 2,6= 455,0832
=15,6 x10 x26 -156 x 26 / 15,6 x 3,3 x 3,4 x 2,6
=156 x 26 - 156 x 26 /
=0 / 15,6 x 3,3 x 3,4 x 2,6
=0
100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
\(\frac{39}{40}-\frac{7}{9}\div\frac{2}{3}\left(\times\frac{3}{2}\right)\times\frac{2}{7}\)\(=\frac{39}{40}-\frac{7\times3\times2}{3\times3\times2\times7}=\frac{39}{40}-\frac{1}{3}\)\(=\frac{117}{120}-\frac{40}{120}=\frac{77}{120}\)
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\(\frac{20}{63}\div\frac{8}{9}\left(\times\frac{9}{8}\right)+\frac{5}{6}\times\frac{51}{70}=\frac{5\times4\times9}{9\times7\times4\times2}+\frac{5\times17\times3}{3\times2\times5\times14}\)\(=\frac{5}{14}+\frac{17}{28}=\frac{10+17}{28}=\frac{28}{28}=1\)
Bài 2 : Tính nhanh
a ) ( 8 , 7 x 29 + 8, 7 x 35 ) : 64
= [ 8.7 x ( 29 + 35 ) ] : 64
= [ 8.7 x 64 ] : 64
= 8.7
b ) 372 x 9 + 372
= 372 x ( 9 + 1 )
= 372 x 10
= 3720
c ) 37 x 24 + 37 x 76 + 63 x 79 + 63 x 21
= 37 x ( 24 + 76 ) + 63 x ( 79 + 21 )
= 37 x 100 + 63 x 100
= 100 x ( 37 + 63 )
= 100 x 100
= 10000
d ) 42 x 53 + 47 x 156 - 47 x 114
= 42 x 53 + 47 x ( 156 - 114 )
= 42 x 53 + 47 x 42
= 42 x ( 53 + 47 )
= 42 x 100
= 4200
hok tốt nha
a) (8,7 x 29 + 8,7 x 35) : 64
= [8,7 x (29 + 35)] : 64
= (8,7 x 64) : 64
= 8,7 x (64 : 64)
= 8,7 x 1 = 8,7
b) 372 x 9 + 372 = 372 x (9 + 1)
= 372 x 10 = 3720
c) 37 x 24 + 37 x 76 + 63 x 79 + 63 x 21
= 37 x (24 + 76) + 63 x (79 + 21)
= 37 x 100 + 63 x 100
= (37 + 63) x 100
= 100 x 100 = 10000
d) 42 x 53 + 47 x 156 - 47 x 114
= 42 x 53 + 47 x (156 - 114)
= 42 x 53 + 47 x 42
= 42 x (53 + 47)
= 42 x 100
= 4200
121 :x =11
x=121:11
x=11
20+x=300+60
20+x=360
x=360-20
x=340
25x10-3
=250-3
=247
121 : x = 11
x = 121 : 11
x = 11
20 + x = 300 + 60
20 + x = 360
x = 360 - 20
x = 340
25 x 10 - 3 = 250 - 3
= 247
300 : x - 20 : x = 70
=> (300-20):x =70
=> 280 : x= 70
=> x = 280 : 70 = 4
x-63.11 = 156.402
=> x-693 = 62712
=> x=62712+69363405
x : 100 = 15,6
=> x=15,6 . 100 = 1560
\(x=15,6\times100\)
\(x=1,560\)