SOLUTION: Pocket change: Harry has $2.25 in nickels, dimes, and quarters. If he had twice as many nickels, half as many dimes and the same number of quarters, he would have $2.50. If he h

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Pocket change: Harry has $2.25 in nickels, dimes, and quarters. If he had twice as many nickels, half as many dimes and the same number of quarters, he would have $2.50. If he h      Log On


   



Question 187158: Pocket change: Harry has $2.25 in nickels, dimes, and quarters. If he had twice as many nickels, half as many dimes and the same number of quarters, he would have $2.50. If he has 27 coins altogether, then how many of each does he have?



2) Three digit number: The sum of the digits of a three-digit number is 11. If the digits are reversed, the new number is 46 more than 5 times the old number. If the hundreds digit plus twice the tens digit is equal to the units digit, then what is the number?

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let n = number of nickels
Let d= number of dimes
Let q= number of quarters
given:
(1) 5n+%2B+10d+%2B+25q+=+225
(2) 5%2A2n+%2B+10%2A%281%2F2%29%2Ad+%2B+25q+=+250
(3) n+%2B+d+%2B+q+=+27
-----------------------
There are 3 unknowns and 3 equations, so it's solvable
(2) 5%2A2n+%2B+10%2A%281%2F2%29%2Ad+%2B+25q+=+250
(2) 10n+%2B+5d+%2B+25q+=+250
Subtract (1) from (2)
(2) 10n+%2B+5d+%2B+25q+=+250
(1) -5n+-+10d+-+25q+=+-225
(4) 5n+-+5d+=+25
(4) n+-+d+=+5
(4) d+=+n+-+5
And, from (3),
(3) n+%2B+d+%2B+q+=+27
(3) q+=+-n+-+d+%2B+27
From(1)
(1) 5n+%2B+10d+%2B+25q+=+225
(1) n+%2B+2d+%2B+5q+=+45
(1) n+%2B+2%2A%28n+-+5%29+%2B+5%2A%28-n+-d+%2B+27%29+=+45
(1) n+%2B+2n+-+10+-+5n+-+5d+%2B+135+=+45
(1) -2n+-+5d+=+-80
(1) -2n+-+5%2A%28n+-+5%29+=+-80
(1) -2n+-5n+%2B+25+=+-80
(1) -7n+=+-105
(1) +n+=+15
and
(4) d+=+n+-+5
(4) d+=+10
and
(3) q+=+-n+-+d+%2B+27
(3) q+=+-15+-+10+%2B+27
(3) q+=+-25+%2B+27
(3) q+=+2
Harry has 15 nickels, 10 dimes, and 2 quarters
check:
(1) 5n+%2B+10d+%2B+25q+=+225
(1) 5%2A15+%2B+10%2A10+%2B+25%2A2+=+225
(1) 75+%2B+100+%2B+50+=+225
(1) 225+=+225
OK