Question 107544
A collection of 40 dimes and nickels is worth $2.90. How many nickels are there?
I came up with this equation:
(d=dimes)
0.1d + 0.05(40-d)= 2.9
:
What you have should work, continuing:
.1d + 2 - .05d = 2.9; multiplied what's inside the brackets
.1d - .05d = 2.9 - 2
.05d = .9
d = .9/.05
d = 18 dimes
and
40 - 18 = 22 nickels
:
:
Check by subsitution:
.1(18) + .05(22) = 
1.8 + 1.1 = 2.9