The average height of a mango tree, a starfruit tree and a persimmon tree is 5.8 m. The persimmon tree is four times as tall as the starfruit tree and 0.6 m taller than the mango tree. Find the average height of the mango tree and the starfruit tree.
Total height of the mango tree, the starfruit tree and the persimmon tree
= 3 x 5.8
= 17.4 m

Height of the starfruit tree = 1 u
Height of the persimmon tree = 4 u
Height of the mango tree = 4 u - 0.6

Total height of the mango tree, the starfruit tree and the persimmon tree
= 1 u + 4 u + 4 u - 0.6
= 9 u - 0.6

9 u - 0.6 = 17.4
9 u = 17.4 + 0.6
9 u = 18

1 u = 18 ÷ 9 = 2

Total height of the mango tree and the starfruit tree
= 1 u + 4 u - 0.6
= 5 u - 0.6
= 5 x 2 - 0.6
= 10 - 0.6
= 9.4 m

Average height of the mango tree and the starfruit tree
= 9.4 ÷ 2
= 4.7 m

Answer(s): 4.7 m