Math help with algebra, please

Question

In the system below, what is the value of k if x equal four times the value of y? What is the solution of the system?

x+y=k

9x-6k= -3

Answer 1

x = 4y

x + y = k

9x - 6k = -3

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4y + y = k

9(4y) - 6k = -3

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5y = k

36y - 6k = -3

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36y - 6(5y) = -3

36y - 30y = -3

6y = -3

y = -3/6 = -1/2

5(-1/2)= k

-5/2 = k

x + y = k

x + -1/2 = -5/2

x + -1/2 + 1/2 = -5/2 + 1/2

x = -4/2 = -2

x=-2

y = -1/2

k = -5/2