9.
A triangle has sides with lengths of 9 m, 12 m and 15 m.

perimeter = 36m

Step-by-step explanation:

Its perimeter is 9 + 12 + 15 = 36m

to find the perimeter of the rectangle this is the expression:

x-9+x-9+3x-4+3x-4=138

if we simplify it:

8x-26=138

remember, 138 is what it all adds up to

the length is 11.5cm

the width is 57.5cm

the area is 661.25cm^2

the answers might not be correct use at own risk

b). 4320 have a nice day