SOLUTION: I need to know how to set up this equation. Please explain the logic behind how you set it up. A purse contains $3.75 in 5 cent and 20 cent coins. there are 33 coins all together.

Question 874334: I need to know how to set up this equation. Please explain the logic behind how you set it up. A purse contains $3.75 in 5 cent and 20 cent coins. there are 33 coins all together. How much of each coin is there?
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
A purse contains $3.75 in 5 cent and 20 cent coins. there are 33 coins all together. How much of each coin is there?
.
Let x = number of 5 cent coins
and y = number of 20 cent coins
then
from "A purse contains $3.75" we get:
.05x + .20y = 3.75 (equation 1)
and from "there are 33 coins" we get:
x + y = 33 (equation 2)
.
Solve equation 2 for y:
x + y = 33
y = 33-x
.
Substitute above into equation 1 and solve for x:
.05x + .20y = 3.75
.05x + .20(33-x) = 3.75
.05x + 6.60 - .20x = 3.75
6.60 - .15x = 3.75
-.15x = -2.85
x = -2.85/(-.15)
x = 19 (number of 5 cent coins)
.
number of 20 cent coins:
y = 33-x = 33-19 = 14

RELATED QUESTIONS
I have no idea how to set up this problem! Once the equation is set up i know how to... (answered by Electrified_Levi)

A coin purse contains 46 coins in dimes and quarters. The coins have a value of $7.00 or... (answered by richwmiller)

If $7000 is invested at 8% compounded monthly, how much will this amount be at the end of (answered by jim_thompson5910)

y=x2+4x+3 Graph using Quadratic Equation. I have a calculator but I really don't know... (answered by jim_thompson5910)

Soymeal contains 16% protein. Cornmeal contains 8% protein. How many pounds of each would (answered by nerdybill)

$3.75 is made up of quarters and half dollars. If the number of quarters exceeds the... (answered by josgarithmetic,MathTherapy,ikleyn)

I need help mulitplying this problem. I dont know how to set it up and show my work.... (answered by CharlesG2)

I don't know how to set this problem up and i can solve it on my own if you could just... (answered by ankor@dixie-net.com)

Basketball Scoring: In a recent game of the 2004-2005 basketball season, the San Antonio... (answered by stanbon)