Hi Jessica Tan,

Below is my worked solution:

u---> units

Yellow : Red

2 : 3

3/4 of the red beads were given away, thus we change the 3 units of red to 12 units as it is then possible to divide it by 3/4. Yellow beads would then be 2 x 4 = 8 while Red beads would be 3 x 4 = 12.

1/4 x 12= 3

3+8=11 (units of total of red beads and yellow beads at the end)

11u+1/2 blue beads --> 920

22u+1 blue beads--> 920 x 2 =1840

12+8=20 (units)

22-20=2(units)

However, if we add up the units for the red beads and the yellow beads, the total is only 20 units. Thus there was an extra of 2 units between 1680 and 1840.

1840-1680=160

2 units-->160

1 unit--> 160/2=80

12 units-->80x12=960 (ans)

There are total of 12 units for red beads at first.

Cheers,

KJ