Answer:
3a+6
Step-by-step explanation:
3a+6 = 24a+48 divided by 8 (there are 8 sides in an octagon)
covert 24a +48 inches into feet
2a+4 feet = 18 feet
subtract 4 from both sides
2a = 14
divided 2 from both sides
a = 7
covert 3a+6 inches into feet
0.25a +0,5
0.25(7)+0.5
= 2.25
verify your answer
2.25 x 8 = 18