Problema Solution
A retailer wishes to mix two grades of rice of the P11 and P15 kinds in orderto obtain a mixture of 120 kilograms of rice if the mixture will be sold at P12 per kilogram how many kilogram of each grades must he use?
Answer provided by our tutors
Let the retailer use x kg of grade P11 and y kg of grade P15.
From the question we know, x+y=120 --------------------------------(i)
and 11x+15y=12*120
11x+15y=1440 ------------------(ii)
Multiply (i) by -15 , so we get
-15x-15y=-1800 ---------------(iii)
Adding (ii) and (iii),
11x+15y-15x-15y=1440-1800
-4x=-360
x=360/4=90
from (i) , y=120-x=120-90=30
So the retailer uses 90 kg of P11 and 30 kg of P15.