In a coin box, the ratio of the number of gold beads to the number of pink beads was 1 : 4. Each time, 5 gold and 7 pink beads were taken out of the coin box. A while later, only 117 pink beads were left in the coin box. What was the total number of beads in the coin box at first?

	Gold beads	Pink beads
Before	1x5 = 5 u	4x5 = 20 u
Change	- 5 u	- 7 u
After	0	117

Since there is no gold beads left, this means that the number of gold marbles at first is the same as the number of gold marbles taken out.  

Make the number of gold beads at first and taken out the same.  LCM of 1 and 5 is 5.

Number of pink beads in the end
= 20 u - 7 u
= 13 u

13 u = 117

1 u = 117 ÷ 13 = 9

Total number of beads in the coin box at first
= 5 u + 20 u
= 25 u
= 25 x 9
= 225

Answer: 225