Hello Henriettas,
Solve for y from first equation
4x - y = 7------------------->(first equation)
-4x -4x (subtract 4x from both sides)
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-y = -4x + 7
(-1)(-y) = (-1)(-4x + 7) (multiply by -1 on both sides)
y = 4x - 7
Now, substitute the value of y in second equation and solve for x.
13x + 17y = 43 --------------->(second equation)
13x + 17(4x - 7) = 43
13x + 68x - 119 = 43 (distribute 17 inside the bracket)
81x - 119 = 43
+119 119 (add 119 on both sides)
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81x = 162
81x/81 = 162/81
x = 2
Now, to solve for y substitute the value of x in first equation
4x - y = 7
4(2) - y = 7
8 - y = 7
-8 -8
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-y = -1
y = 1
Thus, the value of x = 2 and y = 1 are the answers.
