# the infirmary

#### SILVER

##### New member
how do I solve this problem? Is it a problem with 2 unknowns? or just a normal equation?

At the infirmary, four aspirin and five bandages cost a total of $49. Four aspirin and eight bandages cost$64. How much does an aspirin cost?

#### masters

##### Full Member
SILVER said:
how do I solve this problem? Is it a problem with 2 unknowns? or just a normal equation?

At the infirmary, four aspirin and five bandages cost a total of $49. Four aspirin and eight bandages cost$64. How much does an aspirin cost?

Hi Yo Silver,

It will be a system of 2 linear equations.

Let a = cost of aspirin

Let b = cost of bandage

[1] $$\displaystyle 4a\:+\:5b\:=\:49$$
[2] $$\displaystyle 4a\:+\:8b\:=\:64$$

Subtract the two equations:

[3] $$\displaystyle -3b\:=\:-15$$

[3] $$\displaystyle \boxed{b\:=\:\\:5.00}$$

Substitute this answer into [1] or [2] to find a.

Thanks a ton