Question

Over the last three evenings, Donna received a total of 129 phone calls at the call center. The third evening, she received 3 times as many calls as the first

evening. The second evening, she received 9 more calls than the first evening. How many phone calls did she receive each evening?​

Answer 1

Number of calls received in 1st evening = 24

Number of calls received in 2nd evening = 33

Number of calls received in 3rd evening = 72

Explanation:

Let

number of calls received in first evening be "x"

number of calls received in 2nd evening be "y"

number of calls received in 3rd evening be "z"

Total, in 3 evenings, we have 129 phone calls, so we can write:

x + y + z = 129

3rd evening, 3 times as first evening. We can write:

z = 3x

2nd evening, 9 MORE THAN FIRST. So we can write:

y = 9 + x

Now we replace 2nd and 3rd equation in 1st equation to get:

x + y + z = 129

x + 9 + x + 3x = 129

Now, first, we solve for x:

`x + 9 + x + 3x = 129\\5x+9=129\\5x=120\\x=24`

Solving for y:

y = 9 + x

y = 9 + 24

y = 33

Solving for z:

z = 3x

z = 3(24)

z = 72

Thus,

Number of calls received in 1st evening = 24

Number of calls received in 2nd evening = 33

Number of calls received in 3rd evening = 72