A total of 28 purple pens and green pens are in a container. The ratio of purple pens to green pens was 1 : 6. Some gold pens and yellow pens were put into the container. For every 2 green pens that were already in the container, 5 yellow ones were added. Then, the final number of purple pens and gold pens was ³₇ the final number of green pens and yellow pens. Find the total number of gold and yellow pens.

Gold pens	Purple pens	Green pens	Yellow pens
	1x1	6x1
		2x3	5x3
3x3		7x3
8 u	1 u	6 u	15 u

The number of green pens is repeated.  Make the number of green pens the same.  LCM of 6 and 2 is 6.

The total number of green pens and yellow pens is repeated.  Make the total number of green and yellow pens the same.  LCM of 21 and 7 is 21.

Total number of purple pens and green pens
= 1 u + 6 u
= 7 u

7 u = 28

1 u = 28 ÷ 7 = 4

Total number of gold and yellow pens
= 8 u + 15 u
= 23 u
= 23 x 4
= 92

Answer(s): 92