Question

what is the value of y in the solution to the system of equations?x y = 12x – 3y = –30

Answer 1

x + y = 12 . . . . . . . . (1)
x - 3y = -30 . . . . . . . (2)
(1) - (2): 4y = 42
y = 10.5

Answer 2

Answer:

$y=10.5$

Step-by-step explanation:

we have

$x+y=12$ ------> equation A

$x-3y=-30$ ------> equation B

Multiply by $-1$ equation A

$-1*(x+y)=-1*12$ -------> $-x-y=-12$ ------> equation C

Adds equation B and equation C

$x-3y=-30\\-x-y=-12\\ -----------\\-3y-y=-30-12\\-4y=-42\\y=42/4\\ y=10.5$