Question

Together, Aanya and Krish can wash and wax Aanya's car in 50 minutes. Alone it takes Krish ten minutes more than Aanya. To the nearest minute, find the number of minutes it takes for each of them to wash and wax the car alone.

Answer 1

95 ; 105

Explanation:

Let :

Aanya's time = x

Krish's time = x + 10

Together = 50

Hence

Aanya's rate = 1/x

Krish's rate = 1/(x + 10)

Together rate = 1/50

Hence,

1/x + 1/(x + 10) = 1 / 50

((x + 10) + x) / x(x + 10) = 1/ 50

(2x + 10)/ x² + 10x = 1/50

50(2x + 10) = x² + 10x

100x + 500 = x² + 10x

x² + 10x - 100x - 500 = 0

x² - 90x - 500 = 0

Using the quadratic equation solver :

x = 95.24 ; x = - 5.24

Time can't be negative

Hence, x = 95 (nearest minute)

It takes Aanya 95 minutes Alone a ND

Krishna (95 + 10) = 105 minutes alone