7 pencils cost $0.89. How much would 12 pencils cost?

Question

I wasn't in class when this was taught, and I have no idea how to do this. Please somebody help.

Answer 1

7/0.89 = 12/p

 

Cross multiply.

 

7p = 10.68

p = 1.53

 

Twelve pencils would cost $1.53.

Answer 2

try using a proportion, equating the ratio of money to # of pencils, using the given data (including x amount of money for 12 pencils).

Answer 3

Dear Somebody:

 

  If 7 pencils    cost    $0.89

 

So if you want 12 pencils   it would be  the total of 12 pencils  the GRAND TOTAL   Minuus

 

what youhave wich is the seven pencils   which is  (12-7) =5 pecils for what your are looking for.

 

in other words     12

                             ___

                              12            =100% or the grand total.      so:   wehave

 

                  5      =0.89

              ____      _____

                12           1                          Multiply the top   giving       $4.45

                                                                                                       _____            

                                                                                                          12                                                                                                =     $0.37       for the 5 remaining pencils     

 

So, we have the   $0.89       ( for the seven   pencils)                           

 

plus the                 $0.37       ( for the cost of the remaining you seek)         

 

Giving a total of    $1.26     for the entire cost of all the 12 pencils.

 

 

I hope this helps !