Question 72738
<pre>

A line has a slope of 3. One of the points on the line is (2,-3). Another point on the line is (5,p). Find p.

We can use slope formula

          {{{y[2] - y[1]}}}
   m  =  ____________  
          {{{x[2] - x[1]}}}

   m = 3
 ({{{x[2]}}}, {{{y[2]}}}) = (2, 3) ,          
  and ({{{x[1]}}}, {{{y[1]}}}) = (5, p)


Substitute the given values to the formula
       
          3 - p
   3  =  _______  
          2 - 5

  

     
          3 - p
   3  =  _______  
           -3

Multiply -3 both sides

        
              3 - p
 (-3)  3  =  _______  (-3)
                -3


       9  =  3 - p
      
    9 - 3 = 3 - p - 3   subtract both sides by 3

       6 = -p           divide both sides by -1

      -6 = p


Check to be sure your answer is correct.