Xavier's and Usha's monthly allowances were the same at first. Xavier's allowance increased by 50% while Usha's decreased by 40%. Given that Xavier's allowance would decrease by another 40% if he had received $1686 less from his mothers, find the difference in the children's monthly allowances.

	Xavier	Usha
Before	1 u	1 u
Change 1	+ 0.5 u	- 0.4 u
After 1	1.5 u	0.6 u
Change 2	- 0.6 u	No change
After 2	0.9 u	0.6 u

Increase in Xavier's allowance
= 50% x 1 u
= ⁵⁰₁₀₀ x 1 u
= 0.5 u

Decrease in Usha's allowance
= 40% x 1 u
= ⁴⁰₁₀₀ x 1 u
= 0.4 u

Decrease in Xavier's allowance if he had received $1686 less from his mothers
= 40% x 1.5 u
= ⁴⁰₁₀₀ x 1.5 u
= 0.6 u

0.6 u = 1686

1 u = 1686 ÷ 0.6 = 2810

Difference in the allowance between Xavier and Usha
= 1.5 u - 0.6 u
= 0.9 u
= 0.9 x 2810
= $2529

Answer(s): $2529