Answer: 28 shirts
Explanation:
From the question, we are informed that Lisa sold 11 shirts for every 7 shirts Becky sold. This can be expressed in a fraction as:
Lisa = 11/(11 + 7) = 11/18
Becky = 7/(11 + 7) = 7/18
If the girls sold 72 shirts in all, the number of shirts sold by Becky will be:
= 7/18 × 72
= 7 × 4
= 28