Question

Sue and her brother wanted to buy 25 pieces of candy for their family's stockings. They chose to buy Kit Kats and Skittles. After shopping they spent $ 20.70. Skittles

cost 80 cents each and kit kats cost 90 cents each. How many of each candy did they get at the store? Let s-skittles and k=kit kats.
Which systems of equations represents this situation?

Answer 1

18 Skittles and 7 Kit Kats

Linear system of equations in two variables

Explanation:

We a linear system of two equations which can be solved simultaneously

Total pieces of candy equation
s + k = 25 [1]

Total cost equation
0.8s + 0.9k = 20.70 [2]

Multiply [1] by 0.80
0.80s + 0.80k = 20 [3]

Subtract [3] from [2]

0.80s + 0.90k = 20.70

`-`
0.80s + 0.80k = 20

`\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots\cdots`
0.1k = 0.70

k = 0.70/0.10 = 7

In [1]

`s + 7 = 25\\\\s = 25-7\\\\s = 18\\\\`

Answer: 18 Skittles and 7 Kit Kats