Question 69618
X+Y=500 X=500-Y
10X+12Y=5750 NOW REPLACE X WITH (500-Y) & SOLVE FOR Y
10(500-Y)+12Y=5750
5000-10Y+12Y=5750
2Y=5750-5000
2Y=750
Y=750/2
Y=375 THE NUMBER OF $12 CD'S.
NOW SUBSTITUTE 12 FOR Y & SOLVE FOR X
X=275=500
X=500-275
X=225 THE NUMBER OF $10 CD'S.
PROOF
10*225+12*275=5750
2250+3300=5750
5750=5750