I reccomend that you add an image or better explain what you want us to do.
Answer:
r=3 ft
Step-by-step explanation:
it is similarity of two triangles
one
perpendicular side=10 ft
base=10/2=5 ft
second
perpendicular side=10-4=6 ft
Base r=?

Answer:
6x+2
Step-by-step explanation:
your combine like terms...
so 13x is teh same as -7x
13x-7x= 6x
3 and -1 are the same as well
3-1=2
so teh answer would be
6x+2
It means that 15 times another number equals to your equation.