a: \(\Leftrightarrow8x=108+12=120\)
hay x=15
b: \(\Leftrightarrow6x=60\)
hay x=10
a) 5x + 3x = 120
x . (5+3)= 120
x . 8 = 120
x = 120 : 8
x = 15
c) 7x - 2x = 40
x .(7-2)= 40
x . 5 = 40
x = 40 : 5
x = 8