Answer: Jen has 27 stamps
Explanation:
Let the number of stamps Jack has be y.
Since Jen has 3times of Jack stamps, Jack's stamp is 3×y which is 3y.
Jack's stamp+Jen's stamp= 36
y+3y = 36
4y = 36
y = 9
So Jack has 9 stamps and Jen has 9×3 which is 27 stamps.