Question

For what value of k is the point (9, 8) a solution to the equation 9x - 5y = k?

Answer 1

      9x - 5y = k   Substitute in the x- and y-values (x = 9 and y = 8)
9 (9) - 5(8) = k   Multiply
      81 - 40 = k   Subtract
             39 = k

When k = 39, (9, 8) will be a solution to the equation.