Julian and Albert had 86 notebooks together. Julian had 18 more notebooks than Albert. Both of them sold some of their notebooks. Albert sold 30% less notebooks than what Julian sold. In the end, Albert had half as many notebooks left as Julian. How many notebooks had Julian left?

	Julian (1)	Albert (2)	Make p the same (2)x2 = (3)
Comparing Julian and Albert at first	18 more
Before	52	34	68
Change	- 10 u	- 7 u	- 14 u
After	2 p	1 p	2 p

Number of notebooks that Albert had at first
= (86 - 18) ÷ 2
= 68 ÷ 2
= 34

Number of notebooks that Julian had at first
= 34 + 18
= 52

Number of notebooks that Albert sold in percent
= 100% - 30%
= 70%

70% = ⁷⁰₁₀₀ = ⁷₁₀

Make p the same.

(1) = (3)
52 - 10 u = 68 - 14 u
14 u - 10 u = 68 - 52
4 u = 16

1 u = 16 ÷ 4 = 4

Number of notebooks that Julian had left
= 52 - 10 u
= 52 - 10 x 4
= 52 - 40
= 12

Answer(s): 12