a, 315 + (146 - x) = 401
146 - x = 401 - 315
146 - x = 86
x = 146 - 86
x = 60
a: \(315+\left(146-x\right)=401\)
\(\Leftrightarrow146-x=86\)
hay x=60
b: \(x+251-301=56\)
\(\Leftrightarrow x+251=357\)
hay x=106
b, (x + 251) - 301 = 56
x + 251 = 56 + 301
x + 251 = 357
x = 357 - 251
x = 106
c, x - 72 : 36 = 18
x - 2 = 18
x = 18 + 2
x = 20
d, (x - 45) . 27 = 0
x - 45 = 0 : 27
x - 45 = 0
x - 45 = 0
x = 0 + 45
x = 45