①

1 - ¼ = ¾

After giving away ¼ of the total number white balloons away, he is left with ¾ of the total white balloons.

Now we can think of ¾ as 3 units out of 4.

So we can say that there were 4 units of white balloons at first,1 unit was given away, and 3 units are left.


②
Next,

from the question we know that the ratio of white to red balloons left is 3 : 2

That's basically 3 units of white and 2 units of red balloons.

Since the units of white balloons is the same as above, there is no need to change the ratio.


③

So Mr Wong had 4 units of white balloons at first.

Now, suppose if he only gave 20 red balloons away but not any white balloons, he would have:

188 - 20 = 168 balloons left

That is equal to 4 units of white balloons and 2 units of red balloons, a total of 6 units (4 + 2 = 6)


So 6 units = 168 balloons
1 unit = 168 ÷ 6 = 28 balloons

Number of white balloons left

= 3 units

= 3 x 28

= 84

Number of red balloons at first

= 2 units + 20

= 2 × 28 + 20

= 56 + 20

= 76

Thanks!!!!!