Question 113480
9X+12(100-X)=100*11.25
9X+1200-12X=1125
-3X=1125-1200
-3X=-75
X=-75/-3
X=25 ANSWER. FOR THE POUNDS OF $9 COFFEE USED.
100-25=75 FOR THE POUNDS OF $12 COFFEE USED.
PROOF
9*25+12*75=100*11.25
225+900=1125
1125=1125