Explanation

(1) Solve for x in the second equation.

x - 4y = -1

x - 4y + 4y = -1 + 4y

x = 4y - 1

(2) Replace x with 4y - 1 in the first equation.

3(4y-1) + y = 10

12y - 3 + y = 10

13y - 3 = 10

13y - 3 + 3 = 10 + 3

13y = 13

13y/13 = 13/13

y = 1

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ND17-1-2023