a + b = 9 → b = 9 -a
a*b = 20 → a(9 - a) = 20 → -a2 + 9a = 20 → a2 - 9a + 20 = 0 and factoring, we have (a - 5) (a - 4) = 0
So a = 4 or 5 ....either way, we will be adding the fractions
1/4 + 1/5 = 9 / 20 = .45
$$a*b =\frac{1}{a} + \frac{1}{b} Hence: a*b = (a+b)/(a x b) a+b = 9 , a x b = 20 a*b = 0.45$$
