Solve and check the following equation. 8d + 21 = 12d + 5

d =

Subtract 8d from both sides

21 = 12d + 5 - 8d

Simplify 12d + 5 - 8d to 4d + 5

21 = 4d + 5

Subtract 5 from both sides

21 - 5 = 4d

Simplify 21 - 5 to 16

16 = 4d

Divide both side by 4

16/4 = d

Simplify 16/4 to 4

4 = d

Switch sides

d = 4

Check answer

8d + 21 = 12d + 5

Let d = 4

8 * 4 + 21 = 12 * 4 + 5

Simplify 8 * 4 to 32

32 + 21 = 12 * 4 + 5

Simplify 12 * 4 to 48

32 + 21 = 48 + 5

Simplify 32 + 21 to 53

53 = 48 + 5

Simplify 48 + 5 to 53

53 = 53