The average height of a persimmon tree, a mangosteen tree and a starfruit tree is 4.8 m. The starfruit tree is twice as tall as the mangosteen tree and 0.6 m taller than the persimmon tree. Find the average height of the persimmon tree and the mangosteen tree.
Total height of the persimmon tree, the mangosteen tree and the starfruit tree
= 3 x 4.8
= 14.4 m

Height of the mangosteen tree = 1 u
Height of the starfruit tree = 2 u
Height of the persimmon tree = 2 u - 0.6

Total height of the persimmon tree, the mangosteen tree and the starfruit tree
= 1 u + 2 u + 2 u - 0.6
= 5 u - 0.6

5 u - 0.6 = 14.4
5 u = 14.4 + 0.6
5 u = 15

1 u = 15 ÷ 5 = 3

Total height of the persimmon tree and the mangosteen tree
= 1 u + 2 u - 0.6
= 3 u - 0.6
= 3 x 3 - 0.6
= 9 - 0.6
= 8.4 m

Average height of the persimmon tree and the mangosteen tree
= 8.4 ÷ 2
= 4.2 m

Answer(s): 4.2 m