Question 411981
Madeline has total of 64 coins.
Number of coins:                         
x = number of Quaters 
64-x = number of half dollars.                                   

Value in cents:
25x = Number of cents in quarters
50(64-x) = number of cents in half dollars

Remember that everything has to be changed to cents. So $20.00 has to be changed to cents by multiplying with 100. $20.00 = 20 * 100 = 2000 cents.

{{{25x+50(64-x)=2000}}}
{{{25x+3200+50x=2000}}}
{{{25x-50x=2000-3200}}}
{{{-50x=-1200}}}
{{{x=48}}}
{{{64-x=64-48=16}}}

She has 48 Quarters and 16 Half-dollars.