Question

a man spent 1/10 of his monthly salary on rent and 5/6 of the remainder on household needs. if $1,800 is left, how much is his monthly salary?

Answer 1

after 1/10, 5/6 of the remainder is 5/6 * 9/10 = 45/60 = 3/4

so, x(1 - 1/10 - 3/4) = 1800
3/20 x = 1800
x = 12000

Answer 2

1/2

Answer 3

Solution:
x(1-1/10-5/6)=1800
x-x/10-5x/6=1800
L.c.m=30
30x-3x-25x/30=1800
2x/30=1800
2x=54000
x=27000