Respuesta :

Emilee01
so you only have 3 sides so the perimeter will be length+2width instead of 2length+2 width

l+2w= perimeter 
you know the length of the longest side is 15
15+2w = perimeter
and you also know that he is using 31 feet of fencing 
15+2w = 31
2w = 16
w=8