Bryan, Charlie and Adam have $540.
After Bryan spends ⁵₇ of his money,
Charlie spends ¹₅ of his money and
Adam spends ¹₂ of his money,
they have equal amount of money left.
Find the total amount that the 3 children spend.

	Bryan	Charlie	Adam
Before	7 x 2 = 14 u	5 x 1 = 5 u	2 x 4 = 8 u
Change	- 5 x 2 = - 10 u	- 1 x 1 = - 1 u	- 1 x 4 = - 4 u
After	2 x 2 =  4 u	4 x 1 = 4 u	1 x 4 = 4 u

The lowest common multiple of 2, 4 and 1 is 4.

Fraction of the amount left after Bryan spends his money
= 1 - ⁵₇
= ²₇

Fraction of the amount left after Charlie spends his money
= 1 - ¹₅
= ⁴₅

Fraction of the amount left after Adam spends his money
= 1 - ¹₂
= ¹₂

Make the numerators the same.
2 x 27 x 2 of Bryan's amount = 4 x 15 x 1 of Charlie's amount = 1 x 42 x 4 of Adam's amount
414 of Bryan's amount = 45 of Charlie's amount = 48 of Adam's amount

Total amount that they have at first
= 14 u + 5 u + 8 u
= 27 u

27 u = 540

1 u = 540 ÷ 27 = 20

Amount that Bryan spends
= 14 u - 4 u
= 10 u

Amount that Charlie spends
= 5 u - 4 u
= 1 u

Amount that Adam spends
= 8 u - 4 u
= 4 u

Amount that they spend
= 10 u + 1 u + 4 u
= 15 u
= 15 x 20
= $300

Answer(s): $300