Riordan, Carl and Fred bought some cookies. After Riordan ate ⁵₇ of his cookies, Carl ate ²₃ of his cookies and Fred ate 8 cookies, each of them had the same number of cookies left. Riordan had -7 less cookies than Carl at first.

1. How many cookies did Riordan have at first?
2. How many cookies did the 3 of them buy altogether? 

	Riordan	Carl	Fred
Before	7 u	3x2 = 6 u	2 u + 8
Change	- 5 u	- 2x2 = - 4 u	- 8
After	2 u	1x2 = 2 u	2 u

(a)
The number of cookies that Riordan and Carl each had in the end is the same. Make the number of cookies that Riordan and Carl each had in the end the same.  LCM of 2 and 1 is 2.

Number of cookies that Riordan had less than Carl at first
= 6 u - 7 u
= -1 u

-1 u = -7

1 u = -7 ÷ -1 = 7

Number of cookies that Riordan had at first
= 7 u
= 7 x 7
= 49 

(b)
Total number of cookies that the 3 of them bought
= 7 u + 6 u + 2 u + 8
= 15 u + 8
= 15 x 7 + 8
= 105 + 8
= 113

Answer(s): (a) 49; (b) 113