They give us the coordinate ( x, -1). -1 is the y-value, so we plug that in for the variable y in the equation. We need to find the x-value, so we want to solve for x in the equation.
3x - 4y = 11 → Then, plug in y = -1
3x - 4(-1) = 11 → 4(-1) = -4
3x - (-4) = 11 → Two negatives = a positive
3x + 4 = 11 → Subtract 4 from both sides
3x = 7 → Divide both sides by 3
x = 7/3 is the missing coordinate
