Answer:
4
Step-by-step explanation:
the perimeter is the the total length of the shape. we already know that the two sides is 8, and 3 cm. we also know that the perimeter is 15cm. 8+3 is 11 so we need to figure out the remaining length of the side. 15-11 is 4 so the missing length, c, is 4 cm.
