Shelley and David have a sweet tooth. Shelley spent \$2.65 for 15 sour keys and 2 chocolate bars. David bought 3 chocolate bars and 10 sour keys for \$3.35 at the same store. Find the cost of each chocolate bar and each sour key at this store. If you need 8 chocolate bars and 24 sour keys to give to friends coming to your birthday party, how much will they cost you at this store?

Chocolate bars: $0.95 each

Sour keys: $0.05 each

Total cost for 8 chocolate bars and 24 sour keys: $8.80

Step-by-step explanation:

sour keys=x

chocolate bars=y

15x+2y=2.65

10x+3y=3.35

multiply the second equation by 1.5

15x+4.5y=5.025

2.5y=2.375

y=0.95

Chocolate bars are $0.95 each.

Now substitute the y value in one of the equations

15x+2(0.95)=2.65

15x+1.9=2.65

15x=0.75

x=0.05

Sour keys are $0.05 each.

For the second part of the question, just multiply the number of chocolate bars by the cost and same thing with the sour keys and add them.

Final $8.80