12. a) x/3 = 24/18 If we simplify 24/18 by dividing both the numerator and denominator by 6 we get 4/3 Thus x/3 = 4/3 and since we can directly compare both fractions we can see that x = 4
b) 2/(20 - x) = 3/x We can cross-multiply to get: 3(20 - x) = 2x 60 - 3x = 2x 60 = 5x x = 12
