Set up equations and solve.
You spent $125 on 90 snacks that include fruit and cookies. If fruit cost $2.50 each and cookies cost $1.25 each, how many of each did you buy?
Let number of fruit and cookies, be F and C, respectively
Then we get: F + C = 90 ----- eq (i)
Also, 2.5F + 1.25C = 125 ---- eq (ii)
2F + C = 100 ---- Factoring out GCF, 1.25 in eq (ii) ----- eq (iii)
F = 10 ----- Subtracting eq (i) from eq (iii)
Number of fruit purchased, or F = 10.
Now, it's easy to find number of cookies purchased.