Question

main idea: by adding the eq

1. x - y = 11

2x + y = 19

Explanation:

Step1: Add the two equations

$$(x - y) + (2x + y) = 11 + 19$$
$$3x = 30$$

Step2: Solve for x

$$x = \frac{30}{3} = 10$$

Step3: Substitute x into first equation

$$10 - y = 11$$

Step4: Solve for y

$$y = 10 - 11 = -1$$

Answer:

$x=10$, $y=-1$