Bobby and Vincent have some grey notebooks and some brown notebooks. The number of brown notebooks Bobby has is equal to the number of grey notebooks Vincent has. ¹₄ of Bobby's notebooks are grey and ¹₃ of Vincent's notebooks are brown. There are a total of 40 grey notebooks. Find the total number of notebooks they have.

Bobby		Vincent		Total
Grey	Brown	Grey	Brown
	1x6	1x6
1x2	3x2	2x3	1x3
2 u	6 u	6 u	3 u	17 u

The number of Bobby's brown notebooks and Vincent's grey notebooks is the same.

The number of Bobby's brown notebooks is repeated. The number of Vincent's grey notebooks is repeated.  Make the number of Bobby's brown notebooks and Vincent's grey notebooks the same.  LCM of 3 and 4 is 6.

Number of grey notebooks
= 2 u + 6 u
= 8 u

8 u = 40

1 u = 40 ÷ 8 = 5

Total number of notebooks
= 2 u + 6 u + 6 u + 3 u
= 17 u
= 17 x 5
= 85

Answer(s): 85