Question

Suppose you have 20 coins that total $4.some coins are nickles and sime are quarters .which of the following pairs of equations would you use to find out how many of each coin you have?

Answer 1

So 1 nickle=5 cents
1 quarter=25 sents

q=number of quarters
n=number of nickles so

total is
q+n=20
5n+25q=400 (since 100 cents=1 dollar and 4 dollares=400 cents)

SO THE 2 EQUATIONS WOULD BE
n+q=20
5n+25q=400

so q+n=20
subtract q from both sides
n=20-q
subsitute 20-q for n in the second equation
5(20-q)+25q=400
distribute
100-5q+25q=400
add like terms
100+20q=400
subtract 100 from both sides
20q=300
divide both sides by 20
q=15

thhere are 15 quarters

subsitute 15 for q in first equation

15+n=20
subtract 15 from both sides
n=5

5 nickles
15 quarters