Backyard Designs

A backyard has the perimeter of 144m

b) If the backyard is rectangular, and the lngth is three times the width, what are the dimensions?

c) If the backyard is a triangle, write an algebraic expression for the perimeter and find its dimensions. Triangle is isosceles

d) Which of the two backyard designs have the greatest area?

Please explain how you solved these questions step by step and please show what you did. I will really appreciate your help! Trust me I need it!