The math club had to pay a $12 set up fee for club T-shirts plus $5 per shirt. Formulate an equation. Let s represent the number of t-shirts and C the cost.

A mathematical sentence with an equal sign is called an EQUATION.  It is a relationship showing that two expressions have the same value.  

16 ounces = 1 pound,3(x-5)=16, and 3(2) + 7 = 16-3

fist on the left goes with the third on the right. second on the left goes with the fourth on the right. third on the left goes with the second on the right. the fourth on the left goes with first on the right