Is a triangle with sides of length 6ft., 21ft,. 23ft,. a right traingle? show how you know.

No it is not a right triangle. Because using Pythagorean's Theorem 6 squared, 36, plus 21 squared, 441, is 477. And when you do 32 squared is equals to 529. And therefore 477 is not equal to 529.

To solve this you'll want to isolate x

Start by multiplying each side by 5, do this because x is divided by 5 so we must do the opposite operation to undo it

(x/5-15)*5= x-75

35*5=175

The equation is now x-75=175

Add 75 to each side to have x by itself, the equation becomes x=250

So your answer is D