Painted Pots lets customers choose and paint their own pottery. The store has teapots in multiple sizes. Rebecca chose to paint the largest teapot offered, which cost $18. She also painted 4 small teacups to go with her teapot. Rebecca spent a total of $42 on pottery. Which equation can you use to find c, the cost of each teacup?
What was the cost of each teacup?
$