The perimeters if a triangle is 747 metres. the first side is 45 meters shorter than the second side and the third side is twice the shorter side. find the dimensions of the triangle. asap someone

Let
x-----------> the first side
y-----------> the second side
z----------> the third side

we know that
x+y+z=747------> equation 1
x=y-45------> equation 2
z=2x-----> equation 3
substitute 3 in 1
x+y+[2x]=747-------> 3x+y=747--------> equation 4

resolve the system of equation 2 and equation 4 
x=y-45
3x+y=747

using a graph tool
see the attached figure

the solution is
x=175.5 m
y=220.5 m
z=2x-----> z=2*175.5------> z=351 m

the answer is
x=175.5 m
y=220.5 m
z=351 m