7. $\frac{m}{3}=\frac{m + 4}{7}$

Explanation:

Step1: Cross - multiply

$7m = 3(m + 4)$

Step2: Expand the right side

$7m=3m + 12$

Step3: Subtract $3m$ from both sides

$7m-3m=3m + 12-3m$ $4m = 12$

Step4: Divide both sides by 4

$\frac{4m}{4}=\frac{12}{4}$ $m = 3$

Answer:

$m = 3$