Mom and Xiao Ming went to the watermelon stand to buy three watermelons. The biggest watermelon weighs 8 kg, 1 / 3 heavier than the medium watermelon, and the medium watermelon weighs 50% heavier than the smallest watermelon. If the watermelon costs 0.8 yuan per kg, how much will mom pay?

Hello:
Medium watermelon weight:
8 ÷ (1 + 1 / 3) = 6 (kg)
Minimum watermelon weight:
6 (1 + 50%) = 4 (kg)
Mom pays in total:
0.8 × (8 + 6 + 4) = 14.4 yuan