Answer:
Ms. Yost will have exactly 104 boxes of markers.
Explanation:
We are given an initial value (20 markers) and an increase of that amount (420%). We can convert the percentage to a decimal and then multiply this by the initial value of markers.
We divide the percentage by 100 in order to find the decimal form of it. If we wanted to find the percentage form of a decimal, we would multiply that value by 100 instead of dividing by 100.
Therefore, Ms. Yost will have 84 boxes of markers in total after increasing her original 20 boxes by 420%.
Finally, because she increased her total by 84 boxes, we need to add the initial amount as well.
As a final result, Ms. Yost will have exactly 104 boxes of markers.