Eileen saves dimes and quarters. She has 40 coins, which totaled $6.55, in her bank. How many of each coin does she have?

Question

Eileen saves dimes and quarters. She has 40 coins, which totaled $6.55, in her bank. How many of each coin does she have?

Answer 1

Let D = number of dimes

Let Q = number of quarters

 

40 coins  ==>  D + Q = 40  ==>  D = 40 - Q

 

$6.55 total  ==>  10*D + 25*Q = 655

 

Substitute the value for D in to the second equation

 

10*(40 - Q) + 25*Q = 655

400 - 10*Q + 25*Q = 655

15*Q = 255

Q = 17

 

So D = 40 - 17 = 23

 

She has 23 dimes and 17 quarters

 

Check:  23 dimes = $2.30

            17 quarters = $4.25

            Total = $6.55