K-12 Lecture Notes - Lecture 48: Subtraction, Negative Number

I am trying to do subtraction method and i am confused on the subtraction and negative signs... the question is 5x-3y=9 and 2x-y=-3

Question: -12-36

I get really confused subtracting negative integers. They tell meto add the opposite? I don't follow.

-12-36

The sum of two numbers is 0. Twice the smaller number subtracted from 3 times the larger number is 10. Let x represent the larger number and y represent the smaller number. Which equations represent this situation? y = negative x. y = three-halves x minus 5. y = x. y = three-halves x minus 5. y = x. y = two-thirds x + StartFraction 10 Over 3 EndFraction. y = negative x. y = two-thirds x + StartFraction 10 Over 3 EndFraction