There was an equal number of kiwis and starfruits. On Friday, some kiwis were added, such that the number of kiwis increased by 80%. On Saturday, the number of kiwis further increased by 50% and the number of starfruits decreased by 10%. There were 18 more kiwis than starfruits in the end. How many kiwis and starfruits were there altogether at first?

	Kiwis	Starfruits
Before	1 u	1 u
Change 1	+ 0.8 u	No change
After 1	1.8 u	1 u
Change 2	+ 0.9 u	- 0.1 u
After 2	2.7 u	0.9 u

Number of kiwis added on Friday
= 80% x 1 u
= ⁸⁰₁₀₀ x 1 u
= 0.8 u

Number of kiwis increased on Saturday
= 50% x 1.8 u
= ⁵⁰₁₀₀ x 1.8 u
= 0.9 u

Number of starfruits decreased on Saturday
= 10% x 1 u
= ¹⁰₁₀₀ x 1 u
= 0.1 u

Number of more kiwis than starfruits in the end
= 2.7 u - 0.9 u
= 1.8 u

1.8 u = 18

1 u = 18 ÷ 1.8 = 10

Total number of kiwis and starfruits at first
= 1 u + 1 u
= 2 u
= 2 x 10
= 20

Answer(s): 20