The number of safety cones along the road was 50% of the number of trees planted along it. After 63 safety cones and 63 trees were added to the stretch of road, the number of trees became 40% more than the number of safety cones. How many trees were there at first?

	Safety Cones	Trees	Difference
Before	1x2 = 2 u	2x2 = 4 u	1x2 = 2 u
Change	+ 63	+ 63
After	5x1 = 5 u	7x1 = 7 u	2x1 = 2 u

50% = ⁵⁰₁₀₀ = ¹₂

Number of safety cones in the end in percentage = 100%

Number of trees in the end in percentage
= 100% + 40%
= 140%

140% = ¹⁴⁰₁₀₀ = ⁷₅ 

Since the number of safety cones and trees added is the same, the difference in the number of safety cones and trees remains unchanged. LCM of 1 and 2 is 2.

Number of safety cones added
= 5 u - 2 u
= 3 u

3 u = 63

1 u = 63 ÷ 3 = 21

Number of trees at first
= 4 u
= 4 x 21
= 84

Answer(s): 84