Atank can be filled by three pipes separately in 20,30,and 60 minutes respectively. in how many minutes can it be filled by the three pipes acting together

56.6

step-by-step explanation:

the ratio of the perimeters is equal to the scale.

the ratio of the areas is equal to the square of the scale.

34 / 20 = k

a / 19.6 = k²

substituting:

a / 19.6 = (34 / 20)²

a = 19.6 (34 / 20)²

a ≈ 56.6

step-by-step explanation:

hans did not square the 40-unit side; he merely multiplied it by 2.   incorrect.

$15 each

step-by-step explanation:

$45/3 children= $15 each