Total Time = (Worker 1 * Worker 2) / (Worker 1 + Worker 2)
30 = (X*.5X) / (x + .5X)
30 = .5 X^2 / 1.5X
45 X = .5 X^2
Dividing both sides by X
45 = .5 X
X = 90
Stan will take 90 ,minutes and Hilda can do it in 45 minutes.
We can check this by putting the numbers in the formula:
30 = (45 * 90) / (45 + 90)
30 = 4,050 / 135
4,050 = 4,050
Answer is correct.