Question 551946: mr.magoo's piggy bank contains 46 dimes and quarters. The value of his coins is $6.70. how many of each type of coin does he have? Answer by TutorDelphia(193) (Show Source):
You can put this solution on YOUR website! So we know two basic facts:
d+q=46 (the number of dimes plus the number of quarters in 46)
And the values add up to 6.70
d*.10+q*.25=6.70
Now its easy to see this is a systems of equations problem. You can solve it with substitution or elimination.
I'll use elimination.
d+q=46
d*.10+q*.25=6.70 (divide both sides by .1 (which happens to be the same as multiplying by 10))
d+q*2.5=67
d+q=46 subtract this equation from the other one
q*1.5=21
q=14
sub in for q
d+14=46
d=32
If you did it by substitution you'd have to solve the equation:
(46-q)*.10+q*.25=6.70
