A box contains $7.80 in nickels, dimes, and quarters. There are 46 coins in all, and the sum of the numbers of nickels and dimes is 2 less than the number of quarters. How many coins of each kind are there?

Question

Here is my work so far:
x + y + z = 46
x + y = z - 2
.5x + .10y + .25y = 7.80

Answer 1

Typo...
.5x + .10y + .25y = 7.80

is actually

.5x + .10y + .25z = 7.80

Answer 2

no, it is actually

.05x + .10y + .25z = 7.80

Now solve 'em!

Answer 3

x+y+z=46
x+y=z-2
.05x+.10y+.25z=7.80

x+y=z-2
z=x+y+2

x+y+x+y+2=46
2x+2y=44

Does this look right so far..?

Answer 4

a farmer has 500 feet of fence with which to fence a rectangular plot of land. The plot lies along a river so that only three sides need to be fenced. Estimate the largest area that can be fenc