Vaidev and David had 215 staplers together. Vaidev had 13 more staplers than David. Both of them sold some of their staplers. David sold 10% less staplers than what Vaidev sold. In the end, David had half as many staplers left as Vaidev. How many staplers had Vaidev left?

	Vaidev (1)	David (2)	Make p the same (2)x2 = (3)
Comparing Vaidev and David at first	13 more
Before	114	101	202
Change	- 10 u	- 9 u	- 18 u
After	2 p	1 p	2 p

Number of staplers that David had at first
= (215 - 13) ÷ 2
= 202 ÷ 2
= 101

Number of staplers that Vaidev had at first
= 101 + 13
= 114

Number of staplers that David sold in percent
= 100% - 10%
= 90%

90% = ⁹⁰₁₀₀ = ⁹₁₀

Make p the same.

(1) = (3)
114 - 10 u = 202 - 18 u
18 u - 10 u = 202 - 114
8 u = 88

1 u = 88 ÷ 8 = 11

Number of staplers that Vaidev had left
= 114 - 10 u
= 114 - 10 x 11
= 114 - 110
= 4

Answer(s): 4