application problem

Question

You buy 100 candy bars. Some cost $1, some cost $1.50. If they cost $140 total, how many $1 candy bars? I have to write an equation and solve. 

Answer 1

Dear Elizabeth,

 

Y= number of candy bars of one type

X= number of candy bars of a different type

   

 

$1X + $1.5Y = $140        system of equations

   X+Y= 100

  

 

                                     Multiply the bottom equation by -1, and do it to each term on both sides of the equal sign.

 

$1X + $1.5Y = $140 system of equations

-1X  + -1.0Y= -100                      Now you can take the bottom equation from the top.  The "X's" cancel each other out.

   

        .5Y= 40                       Divide both sides of the equation by the number next to "Y."

        

         Y=________

                                         You need to solve for "X" because that is related to $1 candy bars.  Substitute value of 
"Y" back into any equation from the system.

 

-X + - 1 (Y) = -100             Now solve by substituting the "Y" value, and solving for "X." 

 

X=______________                      Answer

                                                               

After you have both values, then substitute into the system of equations to see if your values are correct.

 

If this work helps you, please give me a thumbs.

                                                                           Susan C.