Answer:
Barney got 14 dimes and Betty got 10 quarters.
Step-by-step explanation:
Since there are only dimes and quarters in the parking meter, the total money must be equal to:
[tex]0.1*dimes + 0.25*quarters = 3.9[/tex]
Since Barney got all the dimes and he has four more coins than Betty, then the number of dimes is:
[tex]dimes = quarters + 4[/tex]
Applying the second expression on the first, we have:
[tex]0.1*(quarters + 4) + 0.25*quarters = 3.9\\0.1*quarters + 0.4 + 0.25*quarters = 3.9\\0.35*quarters = 3.9 - 0.4\\0.35*quarters = 3.5\\quarters = \frac{3.5}{0.35} = 10[/tex]
[tex]dimes = quarters + 4 = 10 + 4 = 14[/tex]
Barney got 14 dimes and Betty got 10 quarters.