Question

If 2/5 of a man's income is paid as tax and 2/3 of what is left is spent on food and rent,What portion of his income can he save?

Answer 1

 1 - (2/5 + 3/10 + 1/8 )
=1- (16 + 12 + 5/40)
= 1- 33/40 = 40 - 33/40 = 7 /40 
Let the monthly income = x 
According to the question, 
7/40 x = 2800 
∴ x = 2800 x 40/7 
= 400 x 40 = ₹ 16000
Expenditure on food = 3/10 x 16000 = ₹ 4800 
Expenditure on conveyance = 1/8 x 16000 = ₹ 2000
∴ Expenditure on food and conveyance together 
=₹ (4800 + 2000) = ₹ 6800

Answer 2

Let income = x

Tax = 2x/5

left amount = x - 2x/5 = 3x/5

Food = 3x/5 * 2/3 = 2x/5

Left saving = 3x/5 - 2x/5 = x/5

Saving part = x/5 * 1/x = 1/5

hope it help u