large pies cost $5, and small pies cost $2. if 45 pies were sold for $120, how many small pies were sold ?

Sagot :

Answer:

35 small pies

Step-by-step explanation:

Framing system of linear equations and solving:

  Let the number of large pies be 'l' and

        The number of small pies be 's'.

Total pies sold = 45

⇒  l + s  = 45  ------------(I)

         l = 45 - s  -------(II)

Cost of 45 pies = $120

         Cost of 1 large pie = $5

         Cost of 'l' large pies = 5*l = 5l

    Cost of 1 small pie = $2

   Cost of 's' small pie = 2*s = 2s

         5l + 2s  = 120 --------------(III)

Solving : substitution method

Substitute l = 45 -s in equation (III)

         5*(45 - s) + 2s = 120

       5*45 - 5*s + 2s = 120

        225 - 5s + 2s  = 120   {Combine like terms}

               225 - 3s   = 120

                      -3s     = 120 - 225    {Subtract 225 from both sides}

                           -3s = -105

                              s = -105 ÷ (-3)    {Divide both sides by (-3)}

                             s = 35

Substitute s = 35 in equation (II),

     l = 45 - s

       = 45 - 35

    l = 10

            [tex]\sf \boxed{\text{\bf 35 small pies were sold}}[/tex]