about 0.75 hours
step-by-step explanation:
x = -4
- 20 - 4(x + 3) = 4x
=> -20 - 4x - 12 = 4x
=> - 32 -4x = 4x
=> -32 = 4x + 4x
=> - 32 = 8x
=> -32/8 = x
=> -4 = x