Solve ising substitution method 5x+3y-8=0 and 3x-2y+75=0

The perimeter of a triangle is 69 cm. the first is 5 cm shorter than the second side. the third side is twice as long the first side. find the length of each side

Which statement justifies why angle ebc measures 90?

Me asap on # : explain how factoring a trinomial, ax^2+ bx+ c, when a does not equal 1 different from factoring a trinomial when a = 1.