Fanny spent ¹₈ of her salary on a speaker and ³₅ of the remainder on a vacuum cleaner. If she saved the remaining $420, how much was her salary?
Fraction of the salary spent on the speaker = ¹₈

Fraction of the salary on the remainder
= 1 - ¹₈
= ⁷₈

Fraction of the remainder on savings
= 1 - ³₅
= ²₅

Speaker	Remainder		Total
1x5	7x5		8x5
	Vacuum Cleaner	Savings
	3x7	2x7
5 u	21 u	14 u	40 u

The remainder and the total amount on the vacuum cleaner and the savings are the same. Make the remainder and the total amount on the vacuum cleaner and the savings the same.  LCM of 7 and 5 is 35.

Total salary = 40 u

Amount spent of the speaker = 5 u
Amount spent on the vacuum cleaner = 21 u
Amount of savings = 14 u

14 u = 420

1 u = 420 ÷ 14 = 30

Fanny's salary
= 40 u
= 40 x 30
= $1200

Answer(s): $1200