x = -4
step-by-step explanation:
- 20 - 4(x + 3) = 4x
=> -20 - 4x - 12 = 4x
=> - 32 -4x = 4x
=> -32 = 4x + 4x
=> - 32 = 8x
=> -32/8 = x
=> -4 = x
3.07*10^-4
move the decimal 4 places to the left
.000307