To answer this question you need to understand how to change the description into an equation. I will split the description into two parts like this "if 16 be subtracted from it, 1/7 of the remainder" ----->(X-16) * 1/7 "will be equal to 1/9 of the number"-----> = 1/9*X
If you join them you will get: (X-16) * (1/7)= (1/9)*X x-16= (1/9)*x /(1/7) x-16= 7/9x x- 7/9x= 16 2/9x= 16 x= 16*9/2= 72
