Erin had 55 stuffed bears. She took out her favorite 7 bears and then equally divided the other bears among her 3 sisters. Erin's youngest sister, Su, already had 15 stuffed bears.
How many stuffed bears does Su have now?

Question

Mercury · Answer

thoughts?

Erin starts with 55, then takes away 7 bears, leaving (55 - 7) bears to share amongst the 3 sisters.

divide this quantity by 3 to get each sister's share. this is how many bears Su receives from Erin.

now, since Su already had 15 before this, add 15 to the previous number to get the final result