Questions on Word Problems: Money, Business and Interest answered by real tutors!

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Question 153438: A jar contains 40 Coins consisting of dimes and quarters and having a total value of $4.90. How many of each coin are there?: A jar contains 40 Coins consisting of dimes and quarters and having a total value of $4.90. How many of each coin are there?
Answer by jojo14344(879) About Me  (Show Source):
You can put this solution on YOUR website!
Remember:
Number of dimes = x
Number of quarters = y
So, x+y=40coins ----------------------------------------> eqn 1
Also,
0.10x+0.25y=4.90 ---------------------------------------> eqn 2
In eqn 1 we get, y=40-x, substitute this in eqn 2:
0.10x+0.25(40-x)=4.90
0.10x+10-0.25x=4.90
10-4.90=0.25x-0.10x
5.10=0.15x --------> cross(5.10)34/cross(0.15)=cross(0.15)*x/cross(0.15)
x=34 --------------------------------------> no. of dimes
In eqn 1:
34+y=40 --> y=40-34=6 ----------------> no. quarters
In doubt? Go back eqn 2:
0.10(34)+0.25(6)=4.90
3.40+1.50=4.90
4.90=4.90
Thank you,
Jojo