He has 20 quarters, 15 dimes and 10 pennies.
Step-by-step explanation:
Let,
Quarters = x
Dimes = y
Pennies = z
We know that,
A quarter is 25 cents, dime is 10 cents and penny is 1 cent.
Total amount = $6.60 = 6.60*100 = 660 cents
According to given statement;
25x+10y+z=660 Eqn 1
x=2z Eqn 2
y=z+5 Eqn 3
Putting these values of x and y in Eqn 1
[tex]25(2z)+10(z+5)+z=660\\50z+10z+50+z=660\\61z=660-50\\61z=610\\[/tex]
Dividing both sides by 61;
[tex]\frac{61z}{61}=\frac{610}{61}\\z=10[/tex]
Putting z=10 in Eqn 2
[tex]x=2(10)\\x=20[/tex]
Putting z=10 in Eqn 3
[tex]y=10+5\\y=15[/tex]
He has 20 quarters, 15 dimes and 10 pennies.
Keywords: linear equations, substitution method
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