On January 1, Mario had a savings account balance of $2742 and by April 1, his balance had increased to $3597. Find Mario's average savings rate in dollars per month for that period.

$285

Step-by-step explanation:

First and foremost, we should note that from January 1 to April 1 is 3 months. Since Mario had a savings account balance of $2742 on January 1 and by April 1, his balance had increased to $3597. The increase in balance will be:

= $3597 - $2742

= $855

Then the average savings rate will be:

= Total amount saved / Number of months

= $855/3

= $285

He had an average savings of $285 per month.