The annual income of Rehan is Rs. 672000. He spent 28%

Solution

The annual income of Rehan is Rs. 672000. Monthly income of Rehan = 672000/12= Rs. 56000 He spent 28% of his monthly income on rent. ‘z’% of the remaining monthly income was spent on food by him. If (z-15)% of the remaining monthly income was spent on travelling and remaining money was saved which is equal to Rs. 4032. 56000 of (100-28)% of (100-z)% of (100-(z-15))% = 4032 56000 of 72% of (100-z)% of (100-z+15)% = 4032 56 x 72 x (100-z) x (115-z) = 4032000 (100-z) x (115-z) = 1000 Z²  − 215z + 10500 = 0 Z²   − (140+75)z + 10500 = 0 Z²   − 140z - 75z + 10500 = 0 z(z − 140) - 75(z − 140) = 0 (z − 140) (z − 75) = 0 z = 140, 75 There are two possible values of ‘z’. But as per the options the value of z will be 75.