Tìm x, biết:

a) 2(x – 5) – 3(x + 7) = 14;

b) 7(5 – x) – 2(x – 10) = 15.

a) 2(x – 5) – 3(x + 7) = 14

2x – 2.5 – 3x – 3.7 = 14

−x – 10 – 21 = 14

−x – 31 = 14

x = −31 – 14

x = − 45

Vậy x = − 45.

b) −7(5 – x) – 2(x – 10) = 15

−7.5 + 7x – 2x + 20 = 15

−35 + 20 + 5x = 15

5x = 15 + 15

5x = 30

x = 6

Vậy x = 6.