Joe owns a sandwich shop. He charges $10.00 for two sandwiches and one drink and $6.50 for one sandwich and one drink. How much does Joe charge per sandwich? How much per drink?

Question

What is the solution of the system? Use elimination.
3 − 2 = 5
−2 + = −3

Producing a musical costs $8,000 plus $300 per performance. One sold-out performance earns $700
income. If every performance sells out, how many performances are needed to break even?

In a chemistry lab, you have two vinegars. One is 20% acetic acid and one is 50% acetic acid. You want
to make 200 mL of a vinegar with 30% acetic acid. How many milliliters (mL) of each vinegar do you
need to mix together?

Answer 1

I will only do the third one. You do the others after you see how.
x + y = 200
.2 x + .5 y = .3*200 = 60

let y = 200 - x
.2 x + .5 (200-x) = 60
.2 x + 100 -.5 x = 60
.3 x = 40
x = 40 /.3 = 400/3 = 133 mL of 20%
so 200 - 133 = 67 mL of 50%