3 similar shirts and 4 similar jackets cost $360. 1 such shirt and 3 such jackets cost $220. Find the costof each shirt.

3s + 4j = 360

1s + 3j = 220

This one we can solve using substitution, in that

s + 3j = 220 implies s = 220 - 3j (subtract 3j from each side).

Now substitute into the first equation:

3 (220 - 3j) + 4j = 360. Solve for jackets.

660 - 9j + 4j = 360 [Distributive property]

660 - 5j = 360 [Add - 9j + 4j]

Subtract 360 from each side, and add 5j to each side.

660 - 360 - 5j + 5j = 360 - 360 + 5j

300 = 5j

Divide each side by 5.

$60 = price of a jacket.

Three of these plus a shirt runs $220.

3 (60) = 180

180 + s = 220

180 - 180 + s = 220 - 180 [Subtract 180 from each side]

s = 40

Now we double check.

3 (40) + 4 (60) = 120 + 240 = 360. This satisfies the first equation.

We could check the second one too, but I'm satisfied.