SAT Mathematics Practice Test 7

If $\frac{\mathit{b}}{2}=10$, then multiplying each side of this equation by 2 gives b = 20. Substituting 20 for b in the equation a − b = 12 gives a − 20 = 12. Adding 20 to each side of this equation gives a = 32. Since a = 32 and b = 20, it follows that the value of a + b is 32 + 20, or 52.