l=51
m=78
n=51
n and l have the same value since it’s an isosceles triangle, so that’s why I doubled 4x-9
<span>Find the area of two sides (Length*Height)*2 sidesFind the area of adjacent sides (Width*Height)*2 sidesFind the area of ends (Length*Width)*2 ends<span>Add the three areas together to find the surface area</span></span>
Answer: i dont know
Step-by-step explanation:ok i am srry