The pair of points (6,y) and (10,-1) lie on a line with a slope 1(over)4. what is the value of y?

The formula for Slope is m = where m is the slope and the x's and y's are your given coordinates. So, plug the given information into the formula and solve for y.

m =   Plug in the given values
=    Cross multiply
10 - 6 = -4 - 4y   Subtract
       4 = -4 - 4y   Add 4 to both sides
       8 = -4y        Divide both sides by -4
      -2 = y            Swich the sides to make it easier to read
       y = -2

Check your answer by plugging -2 back into the equation with the other values.

=    Simplify the double negative
=    Simplify the numerator and denominator
= 

Since both sides equal each other, y = -2.

Yes you do, so £1973.09 - £1473.50 = £499.59 so tim overpaid £499.59 .hope this ; )