Solve 2x + 5y = 20; 3x - 10y = 37 by elimination. how do you do this? -you!

Which of the following answers is 7/9 simplified? 7/9 2/9 11/9 2/7

Asap! i'm not good math and i'm lost.

Tomas used 3 1/3 cups of flour and now has 1 2/3cups left. which equation can he use to find f, the number of cups of flour he had to begin with? f+3 1/3=1 2/3 f-3 1/3=1 2/3 3 1/3f=1 2/3 f/3 1/3=1 2/3