Set up a system of equations:
x represents how many tee shirts were bought, and y represents how many long sleeve shirts were bought.
For the first equation, subtract y from both sides to get x by itself:
We'll now use substitution. Since x is equal to a value, we can substitute this value for the other equation:
Distribute the 10 to both terms in parentheses:
Combine like terms:
Subtract 90 from both sides:
Divide both sides by -3 to get y by itself:
6 long sleeve shirts were bought.
Now you have a value for y. Input this value into the first equation:
Subtract both sides by 6 to get x by itself:
3 tee shirts were bought.
The answer is B. 3 tee shirts and 6 long sleeve shirts.
