Math equation and Answer needed . please show work so I know what I'm doing wrong.

Question

Briana and her sister Molly both want to buy the same model bicycle. Briana needs $73 more before she can afford the bike. Molly needs $65 more. If they combine their money, they will have just enough to buy one bicycle that they could share. What is the cost of the bicycle?

Answer 1

First, let's assign variables:

    B = amount of money Briana has

    M = amount of money Molly has

    C = cost of bicycle  (we must find this)

 

Translate:

  "Briana needs $73 more before she can afford the bike."   means   B + 73 = C

  "Molly needs $65 more"                                               means      M + 65 = C

  "... combine their money, ... just enough to buy one bicycle"    means    B + M = C

 

O.K., now the easy math:

Add the first two equations:

        B + 73 = C

        M + 65 = C

   -----------------------

      B + M + 138 = 2C

      B + M           =  C       (use third equation)

  ------------------------       (now, subtract equations)

                  138 = C

 

Answer 2

Briana has B dollars

B+73 will buy the bike

Molly has M dollars

M+65 will buy the bike

B+73=M+65

B+M will buy the bike

B+M=B+73 so M=$73

B+M=M+65 so B=$65

$73+$65=$138 is the cost of the bike

 

Answer 3

Hi Kyla,

 

If Briana needs $73 more and she will have enough if she combines with Molly then Molly must have $73.

 

Likewise, Briana must have $65 same logic as above.

 

therefore the bicycle must cost $73 + $65 = $138