Question

Ally and Beck went fishing and caught a total of 75 fish. At home,

Ally told Jair she caught twice as many fish as she actually caught.
Beck told Jair he caught three times as many fish as he actually
caught. If what they told Jair had been true, then Ally would have
caught 75 fewer fish than Beck. How many fish did Beck actually
catch?

Answer 1

Beck caught 45 fish

Explanation:

a = number of fish Ally caught

b = number of fish Beck caught

They caught a total of 75 fish, so we have:

b + a = 75

From the facts in our question we know Ally would have caught 75 fewer fish than Beck.

3b = 2a + 75

a = 75 - b

3b = 2(75 - b) + 75

3b = 150 - 2b + 75

5b = 225

5b ÷ 5 = 225 ÷ 5

b = 45

Beck caught 45 fish.

Answer 2

Beck actually caught 45 fish

Explanation:

System of Equations

We call the following variables:

x = number of fish Ally caught

y = number of fish Beck caught

They caught a total of 75 fish, thus:

x + y = 75 [1]

If Ally had caught twice as much fish as she actually did, and Beck had caught three times as many fish as he actually did, then Ally would have caught 75 fewer fish than Beck, thus:

3y = 2x + 75 [2]

From [1]:

x = 75 - y [3]

Substituting in [2]:

3y = 2(75 - y) + 75

Operating:

3y = 150 - 2y + 75

Simplifying:

5y = 225

Dividing by 5:

y = 45

Beck actually caught 45 fish