Answer:
The total amount he saved this month=84×3=$252
Explanation:
Last month he saved 21 dollars each week for 4 weeks, to calculate the total amount he saved for the for weeks, we can express this as;
Total amount=Amount he saved per week×Number of weeks
Where;
Amount he saved per week =$21
Number of weeks=4 weeks,
Replacing;
Total amount=21×4=$84
This month he saved 3 times as much money as he saved last month, this can be expressed as;
The total amount he saved this month=Amount saved last month×3
Where; Amount saved last month=$84
Replacing;
The total amount he saved this month=84×3=$252