Question

1. Solve 3x + 3 =21

Answer 1

1.

3x + 3 = 21

3x = 21-3

3x = 18

x = 18/3

Therefore,
x = 6


So option ( B) is the correct one.


2.

$\frac{3x}{2} - 4 = 16 \\ \frac{3x}{2} = 16 + 4 \\ \\ \frac{3x}{2} = 20 \\ 3x = 20 \times 2 \\ 3x = 40 \\ x = \frac{40}{3} = 13 \frac{1}{3}$


Therefore option (B) is the correct one here too.

Answer 2

$1.\\\\3x+3=21\qquad|\text{subtract 3 from both sides}\\\\3x=18\qquad|\text{divide both sides by 3}\\\\\boxed{x=6}\to\boxed{B.}$

$2.\\\\\dfrac{3}{2}x-4=16\qquad|\text{add 4 to both sides}\\\\\dfrac{3}{2}x=20\qquad|\text{multiply both sides by 2}\\\\3x=40\qquad|\text{divide both sides by 3}\\\\x=\dfrac{40}{3}\\\\\boxed{x=13\dfrac{1}{3}}\to\boxed{B.}$