Black pencils cost 5 cents each and coloured pencils 7 cents. If two dozen assorted pencils cost 1.34 dollars, how many are black and how many are coloured?

Question

Black pencils cost 5 cents each and coloured pencils 7 cents. If two dozen assorted pencils cost 1.34 dollars, how many are black and how many are coloured?

Answer 1

There are two sole equations you will need to have.

1) 1.34 = .07x + .05y  2) x + y = 24

 

use the second equation as such : x + y = 24

                                                    - y         - y

                                                x       = 24  - y

 

use this equation above ( x = 24 - y ) to find solve equation 1 by substituting the equation for ( x ) . when you find that information , reverse equation 2 so that you may get the same type of equation instead finding ( y ) . this will help you tremendously in the timing department rather than throwing different numbers out of the clouds.