Atriangular flower bed needs a thin metal border all the way around it. the sides are 7 feet, 6 feet, and 9 feet long.

Excuse my awful triangle drawing skills, haha..
So essentially you need to find the perimeter which is done by adding the lengths of the sides.. this gives you 22ft.
Then for part b you need to convert 22ft to yards which gives you 7.3 yards.
Since you can only buy a whole number of yards, you'll actually need 8 yards.
So if the boarder is $8.75 per yard, and you need 8 yards, how much would it cost?
Hope this was helpful.