Verified Answer :

BLH11

75 i believe is the answer

keep in mind that area of a triangle is: A= bh/2

we know that the area is 15 inches, and the height is 5 inches

A=15
H=5

15 doubled is 30, so we know that before we divided is, it was 30

so - 5___=30 - to figure this out we need to do the opposite of multiplying, which is dividing 

so - 30/5=6

the base is 6, to check our answer, we do this:
H=5       b
h/2
B=6           

bh/2 = 56/2=15

i hope this helped!!