Let a, b, and c be the sides of the triangle from smallest (a) to largest (c).
The ratio of side b to a is:
b 3
--- = ---
a 2
So b = (3/2)a = (1.5)a
The ratio of side c to a is:
c 4
--- = ---
a 2
So c = (4/2)a = 2a
The perimeter is 45 feet:
a + b + c = 45
Substitute 1.5a for b and 2a for c:
a + (1.5)a + 2a = 45
4.5a = 45
a = 10 ft
b = (1.5)a = (1.5)(10) = 15 ft
c = 2a = 2*10 = 20 ft
Check:
10 + 15 + 20 = 45
45 = 45