send help pls sana ma tulongan niyo ako

Answer:
Since the perimeter is 85 lets add up first the 4 side
13.5 + 12.5 = 26 + 26.3 = 52.3 + 25.9 = 78.2
for the mssing side subtract the result from the last step fron 85
85 - 78.2 = 6.3 cm
Step-by-step explanation:
Sana po makatulong Godbless