Bailey buys two shirts. The blue shirt costs $13, which is $2.50 more than the price of the red shirt. What is the cost of the red shirt? Write and solve an equation to find the answer, using

Let x be the cost of the red shirt.

The cost of the blue shirt is $13, which is $2.50 more than the cost of the red shirt:
x + $2.50 = $13
Subtract $2.50 from both sides:
x = $10.50

Therefore, the cost of the red shirt is $10.50.