Amelie solves the following system of equations. x plus y is equal to 20 3 x minus 3 y is equal to 30 Which values of x and y satisfy this system of equations?

Divide the second equation, 3x − 3y = 30, by 3 to get x − y = 10. Adding this to x + y = 20 gives 2x = 30, so x = 15 and y = 5; choice C gives these values.

AI-written and checked against the verified answer.