Question

Andre’s school orders some new supplies for the chemistry lab. The online store shows a pack of 10 test tubes costs $4 less than a set of nested beakers. In order to fully equip the lab, the school orders 12 sets of beakers and 8 packs of test tubes.

1. Write an equation that shows the cost of a pack of test tubes, t, in terms of the cost of a set of beakers, b.

2. The school office receives a bill for the supplies in the amount of $348. Write an equation with t and b that describes this situation.

3. Since t is in terms of b from the first equation, this expression can be substituted into the second equation where t appears. Write an equation that shows this substitution.

4. Solve the equation for b

5. How much did the school pay for a set of beakers? $

6. How much did the school pay for a pack of test tubes? $

Answer 1

10t = b - 4

12b+8t = $348

This is a system of equations. I’ll be solving through substitution.

In the first equation. solving for b (the easier variable to isolate) gives you:

b = 10t + 4

Substitute this into the second equation:

12(10t+4) +8t = 348

120t+48+8t = 348

128t = 300

t = 2.34375 —> round it to the nearest cent to get 2.34 dollars

b = 10t+4

b = 10(2.34)+4

b = 27.4 dollars