Solve for a 7+3a=12+2a

$7 + 3 a = 12 + 2 a$

Move all terms containing $a$ to the left side of the equation.

Subtract $2 a$ from both sides of the equation.

$7 + 3 a - 2 a = 12$

Subtract $2 a$ from $3 a$ .

$7 + a = 12$

Move all terms not containing $a$ to the right side of the equation.

Subtract $7$ from both sides of the equation.

$a = 12 - 7$

Subtract $7$ from $12$ .

$a = 5$