let
x------> the length of a rectangle
y------> the height of a rectangle
we know that
perimeter of a rectangle=2*[x+y]
perimeter of a rectangle=3 ft
convert to in
1 ft-----> 12 in
3 ft-----> x
x=3*12-----> x=36 in
perimeter of a rectangle=36 in
36=2*[x+y]
18=x+y--------> x=18-y-----> equation 1
x=6+y-----> equation 2
equate equation 1 and equation 2
18-y=6+y
2y=18-6
2y=12
y=6 in
x=6+x-----> x=6+6-----> x=12 in
the answer is
the length of a rectangle is 12 in and the height of a rectangle is 6 in
