Question

Tìm x biết:

a)  390 - ( x - 7 ) = 169 : 13                  b) ( x - 140 ) : 7 = 3³ - 2³ . 3

Answer 1

a)

\(390-x+7=13\)

\(\Rightarrow397-x=13\)

\(\Rightarrow x=384\)

b)

\(\left(140-x\right):7=27-24\)

\(140-x=21\)

x=119

Answer 2

a) \(390-\left(x-7\right)=169:13\)

\(390-\left(x-7\right)=13\)

\(x-7=390-13\)

\(x-7=377\)

\(x=377+7\)

\(x=384\)

Vậy \(x=384\)

b) \(\left(x-140\right):7=3^2-2^3\cdot3\)

\(\left(x-140\right):7=-15\)

\(x-140=\left(-15\right)\cdot7\)

\(x-140=-105\)

\(x=\left(-105\right)+140\)

\(x=35\)

Vậy \(x=35\)