(x-15):12=79 dư 8

=>\(x-15=79\times12+8=956\)

=>x=956+15=971

(x - 15) : 12 = 79 dư 8

x - 15 = 79 x 12 + 8

x - 15 = 956

x = 956 + 15

x= 971 

\(\left\{47-\left[736:\left(5-3\right)^4\right]\right\}.2021\)

\(=\left\{47-\left[736:2^4\right]\right\}.2021\)

\(=\left\{47-\left[736:16\right]\right\}.2021\)

\(=\left\{47-46\right\}.2021\)

\(=1.2021\)

\(=2021\)

\(\left\{47-\left[736:\left(5-3\right)^4\right]\right\}\cdot2021\)

\(=\left\{47-736:16\right\}\cdot2021\)

\(=\left(47-46\right)\cdot2021=2021\)

2(x-1)+3(x-2)=x-4

=> 2x-2+3x-6=x-4

=> 5x-8=x-4

=> 5x-x=8-4

=> 4x=4

=> x=4:4

=> x=1

Vậy: x=1

\(2\left(x-1\right)+3\left(x-2\right)=x-4\)

\(2x-2+3x-6=x-4\)

\(\left(2x+3x\right)-\left(2+6\right)=x-4\)

\(5x-8=x-4\)

\(5x-x=-4+8\)

\(4x=4\)

\(x=1\)

\(\left(2345-45\right)+2345\)

\(=2300+2345\)

\(=4645\)

\(\left(2345-45\right)+2345\)

\(=2300+2345\)

\(=4645\)

\(\left(7+x\right)-\left(21-13\right)=32\)

\(\left(7+x\right)-8=32\)

\(7+x=32+8\)

\(7+x=40\)

\(x=40-7\)

\(x=33\)

Vậy \(x=33\)

\(\left(7+x\right)-\left(21-13\right)=32\)

\(7+x-21+13=32\)

\(x+\left(7+13-21\right)=32\)

\(x-1=32\)

\(x=33\)

\(-11-\left(19-x\right)=50\)

\(-11-19+x=50\)

\(x-\left(11+19\right)=50\)

\(x-30=50\)

\(x=50+30\)

\(x=80\)

\(-11-\left(19-x\right)=50\Leftrightarrow19-x=-11-50=-61\Leftrightarrow x=19+61=80\)

Đề bài có vấn đề bạn nhé , phần diện tích đất còn lại ra âm

sai đề rồi bạn ơi!

Người thợ săn trộn số lít sơn xanh và trắng là :
        3,8 + 0,7 = 4,5 ( l )
Người thợ sơn còn lại số lít sơn xanh nhạt là :
       4,5 - 1,25 = 3,25 ( l )
            Đáp số : 3,25l sơn xanh nhạt

= -1+ ( -1 ) + ( -1 ) + ( -1 ) + ( -1 ) 

= -2 + ( -3)

= - 5

chúc bạn học tốt

\(\text{11-12+13-14+15-16+17-18+19-20}\)

\(=\left(-1\right)+\left(-1\right)+\left(-1\right)+\left(-1\right)+\left(-1\right)\)

\(=\left(-1\right).5\)

\(=-5\)

a) \(\dfrac{-3}{5}+\dfrac{28}{5}.\left(\dfrac{13}{56}-\dfrac{5}{24}+\dfrac{1}{7}\right)\\ =-\dfrac{3}{5}+\dfrac{28}{5}.\dfrac{13}{56}-\dfrac{28}{5}.\dfrac{5}{24}+\dfrac{28}{5}.\dfrac{1}{7}\\ =-\dfrac{3}{5}+\dfrac{28.13}{5.2.28}-\dfrac{4.7.5}{5.4.6}+\dfrac{4.7.1}{5.7}\\ =-\dfrac{3}{5}+\dfrac{13}{10}-\dfrac{7}{6}+\dfrac{4}{5}\\ =\dfrac{1}{5}+\dfrac{13}{10}-\dfrac{7}{6}\\ =\dfrac{6}{30}+\dfrac{39}{30}-\dfrac{35}{30}=\dfrac{10}{30}=\dfrac{1}{3}\)

b) \(\dfrac{5}{7}.\dfrac{11}{18}+\dfrac{3}{7}.\dfrac{5}{8}+\dfrac{4}{9}\\ =\dfrac{5}{7}.\dfrac{11}{18}+\dfrac{5}{7}.\dfrac{3}{8}+\dfrac{4}{9}\\ =\dfrac{5}{7}.\left(\dfrac{11}{18}+\dfrac{3}{8}\right)+\dfrac{4}{9}\\ =\dfrac{5}{7}.\dfrac{7}{4}+\dfrac{4}{9}\\ =\dfrac{5}{4}+\dfrac{4}{9}=\dfrac{61}{36}\)

c) \(4\dfrac{5}{9}:\left(\dfrac{-5}{7}\right)+\dfrac{49}{9}:\left(\dfrac{-5}{7}\right)\\=\left(4\dfrac{5}{9}+\dfrac{49}{9}\right):\dfrac{-5}{7}\\ =\left(\dfrac{41}{9}+\dfrac{49}{9}\right).\dfrac{-7}{5}\\ =10.\dfrac{-7}{5}=-14\)

Mình sửa lại câu b nhé:

\(=\dfrac{5}{7}.\dfrac{11}{18}+\dfrac{5}{7}.\dfrac{3}{8}+\dfrac{4}{9}\\ =\dfrac{5}{7}.\left(\dfrac{11}{18}+\dfrac{3}{8}\right)+\dfrac{4}{9}\\ =\dfrac{5}{7}.\dfrac{71}{72}+\dfrac{4}{9}=\dfrac{355}{504}+\dfrac{4}{9}\\ =\dfrac{193}{168}\)