X+y=10 x-y=20 how do you solving systems of equations with elimination

Which ordered pair (c, d) is a solution to the given system of linear equations- c+2d=13 -9c-4d=-15

Which number line correctly shows 0.8 + 0.3?

Triangle abc was translated 2 untits to the right and 3 units down. write the algebraic rule that describes the translation that was applied to triangle abc to create triangle a'b'c'.