in harry's attic there are three spider webs. the first web is twice as large as the second web. gthe third web is 3 inches larger than the first web. the combined width of the three webs is 1 foot and 6 inches. how long is each web?
calling the web sizes f,s,t
f = 2s
t = f+3
f+s+t = 18 (inches)
(f,s,t) = (6,3,9)