Riordan, Ryan and Albert bought some tarts. After Riordan ate ⁴₇ of his tarts, Ryan ate ²₃ of his tarts and Albert ate 5 tarts, each of them had the same number of tarts left. Riordan had 20 less tarts than Ryan at first.

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

	Riordan	Ryan	Albert
Before	7 u	3x3 = 9 u	3 u + 5
Change	- 4 u	- 2x3 = - 6 u	- 5
After	3 u	1x3 = 3 u	3 u

(a)
The number of tarts that Riordan and Ryan each had in the end is the same. Make the number of tarts that Riordan and Ryan each had in the end the same.  LCM of 3 and 1 is 3.

Number of tarts that Riordan had less than Ryan at first
= 9 u - 7 u
= 2 u

2 u = 20

1 u = 20 ÷ 2 = 10

Number of tarts that Riordan had at first
= 7 u
= 7 x 10
= 70 

(b)
Total number of tarts that the 3 of them bought
= 7 u + 9 u + 3 u + 5
= 19 u + 5
= 19 x 10 + 5
= 190 + 5
= 195

Answer(s): (a) 70; (b) 195