Annie and Keith

Question

Annie and Keith have a total of (4n-8) marbles. If Annie has n marbles and the number of Keith's marbles is 2 times that of Annie's, how many marbles does Annie have?

Answer 1

Annie has n marbles

 

Keith has 2n marbles

 

Their total (Annie plus Keith) marbles is 4n - 8

 

Equation   →   n + 2n = 4n - 8

 

                            3n = 4n - 8    subtract 4n from both sides

 

                           -4n   -4n

 

                            -1n = -8       Divide both sides by -1

 

                       -1n/-1  = -8/-1

 

 

                                 n =  8  →   The number of marbles for Annie

 

                                2n = 2(8) = 16   →   The number of marbles Keith has

 

Together the gave 8 + 16 = 24 marbles

 

CHECK

 

4n - 8 is total number of marbles

 

4(8) - 8 =  32 - 8 = 24 marbles   √