Answer:
$108
Explanation:
Let n be the cost of a keychain, then the cost of a T-Shirt would be 4n. We can use this to set up an equation...
4n+n=135
Combine like terms
5n=135
Divide both sides by 5
n=27
Now we need to find how much she made from selling T-Shirts...
4n=4(27)=$108