(9·20+60)÷4−16+4·(20·5)

444

Step-by-step explanation:

Parentheses

Exponents

Multiplication

or

Division

Addition

or

Subtraction

(9·20+60)÷4−16+4·(20·5) -multiply the first numbers in the first ()

(180+60)÷4−16+4·100 - multiply the numbers in the last ()

240÷4-16+4·100 -add the numbers in the ()

240÷4-16+400 -multiply the last numbers

60-16+400 -divide the firsts numbers

444 -SOLVED

2.4 hours.

Step-by-step explanation:

Remark

The supervisor is not quite correct. The correct answer must be lower than the lowest number, otherwise you are taking out what the person with the narrower hose must be taking out what the other person is putting in.

Equation

Let x = the amount of time needed for him to fill the pool

Let y = the amount of time needed for the second person to fill the pool

Let z = the amount of time needed for both to fill the pool.

1/x + 1/ y = 1/z

1/4 + 1/6 = 1/z         The common denominator is 12

3/12 + 2/12 = 1/z

5/12 = 1/z                Cross multiply

5z = 12 * 1               Divide by 5

z = 12/5

z = 2 2/5

z = 2.4 hours