The domain is talking about the "range" of the horizontal axis therefore you will be focusing on the x-intercepts.
The answer will be All non-negative real numbers less than or equal to 18
because the x-intercepts lies at 0 and 18. The answer makes sense because the furthest you can go is 18 ft and the closest you could go is 0 ft. The "all non-negative real numbers" puts a restriction on the least distance it could travel so that means that it stops at 0 ft because if you go any further, you will end up in the negatives and it clearly states "non-negative".
Use the Pythagorean therm , you know the a^2+b^2=c^2
P=2w+(2w-3)
60=4w-3
63=4w
15.75=w
l=2w-3
l=(2×15.75)-3
l=31.5-3
l=28.5
This answer doesn't add up so if you meant the COMBINED width then:
P=w+(2w-3)
60=3w-3
63=3w
21=w
l=2(21)-3
l=42-3
l=39
(This answer checks out so this is probably what you meant hope I helped)
Download photo math you scan you problem and it tells you the answer
