The number of safety cones along the road was 70% of the number of trees planted along it. After 80 safety cones and 80 trees were added to the stretch of road, the number of trees became 25% more than the number of safety cones. How many trees were there at first?

	Safety Cones	Trees	Difference
Before	7x1 = 7 u	10x1 = 10 u	3x1 = 3 u
Change	+ 80	+ 80
After	4x3 = 12 u	5x3 = 15 u	1x3 = 3 u

70% = ⁷⁰₁₀₀ = ⁷₁₀

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

Number of trees in the end in percentage
= 100% + 25%
= 125%

125% = ¹²⁵₁₀₀ = ⁵₄ 

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 3 and 1 is 3.

Number of safety cones added
= 12 u - 7 u
= 5 u

5 u = 80

1 u = 80 ÷ 5 = 16

Number of trees at first
= 10 u
= 10 x 16
= 160

Answer(s): 160