20 - 5 x (2 - x) = 45
5x (2 - x)= 20-45
5x (2 - x)= -25
(2 - x)=(-25) :5
2 - x= -5
x= 2-(-5)
x=2+5
x=7
Vậy x=7
\(20-5\cdot\left(2-x\right)=45\)
\(5\cdot\left(2-x\right)=20-45=-25\)
\(2-x=\left(-25\right):5=-5\)
\(x=2-\left(-5\right)=7\)
Vậy \(x=7\)
\(\#PeaGea\)