53 + (124 - x) = 87
(124 - x) = 87 - 53
(124 - x) = 34
x = 124 - 34
x = 90
12.x - 64 = 25
12.x - 64 = 32
12.x = 32 + 64
12.x = 96
x = 96 : 12
x = 8
\(\text{1)}53+\left(124-x\right)=87\)
\(\left(124-x\right)=87-53=34\)
\(x\) \(=124-34=90\)
\(\text{2)}12.x-64=2^5\)
\(12.x-64=32\)
\(12x\) \(=32+64=96\)
\(x\) \(=96:12=8\)