Preston started the summer owing $15 to his brother and $20 to his sister. He earned $75 mowing lawns, and paid his brother and sister back what he owed them. Which expression represents the amount of money that Preston has after paying back his brother and sister?

$75 - $15 - $20 = $40

Step-by-step explanation:

Given that:

Money owed by Preston to his brother = $15

Money owed by Preston to his sister = $20

Total money earned by Preston = $75

Now, the money is paid back that he owed to his sister and brother.

To find:

The expression to represent the amount of money left with Preston after clearing all his dues?

Solution:

Once Preston pays back the money that he owed to his brother and sister, he will not have all $75 left with him.

He will have lesser amount of money.

Money left with Preston = Total money earned by Preston - Money owed to brother - Money owed to sister

Putting the values given as per the question statement, we get:

Money left with Preston = $75 - $15 - $20 = $40

Therefore, the expression to represent the amount of money left with Preston = $75 - $15 - $20 = $40