SOLUTION: Christy has a coin collection of nickels and dimes. She has 28 coins worth $2.25. How many of each coin does Christy have? I know that .05n + .10D = $2.25 I also know that n+d=

Algebra ->  Human-and-algebraic-language -> SOLUTION: Christy has a coin collection of nickels and dimes. She has 28 coins worth $2.25. How many of each coin does Christy have? I know that .05n + .10D = $2.25 I also know that n+d=      Log On


   

Question 573352: Christy has a coin collection of nickels and dimes. She has 28 coins worth $2.25. How many of each coin does Christy have?
I know that .05n + .10D = $2.25
I also know that n+d=28
I can figure out these types of problems in my head, but I can't seem to do it using an algebraic equation.
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
your equations can be used for substitution or elimination

n + d = 28 ___ n = 28 - d

5n + 10d = 225 ___ substituting ___ 5(28 - d) + 10d = 225

140 - 5d + 10d = 225 ___ 5d = 85

solve for d, then substitute back to find n