150% = 150/100 = 3/2

So let the money Xavier received be 2units.

Ali received 150% of Xavier's + $6
= 3 units + $6

Yi Shen received 1/3 of Ali's + $4
= 1/3 × (3 units + $6) + $4
= 1 unit + $2 + $4
= 1 unit + $6

Yi Shen received $2 less than Xavier. This also means Xavier received $2 more than Yi Shen.

So difference between their amount of money = 2 units - (1 unit + $6)
= 1 unit - $6

1 unit - $6 = $2
1 unit = $2 + $6
1 unit = $8

The sum of money
= 3 units + $6 + 2 units + 1 unit + $6
= 6 units + $12
= 6 x $8 + $12
= $48 + $12
= $60

Amount Ali received
= 3 x $8 + $6
= $24 + 6
= $30

Percentage of money Ali received
= $30/$60 x 100%
= 1/2 x 100%
= 50%

b) Method 1 :

Amount Xavier received = 2 units
= $8 x 2 = $16

Amount Yi Shen received = 1 unit + $6
= $8 + 6 = $14

OR

Amount Yi Shen received = $16 - $2
= $14

Total amount Yi Shen and Xavier have
= $14 + $16 = $30

Amount each of them would receive if the money was divided equally among them

= $30 ÷ 2
= $15

Amount Xavier has to give Yi Shen so they each have the same amount of money

= $16 - $15
= $1

Method 2

Xavier has $2 more than Yi Shen.

So, all he has to do is to give half of that $2
to Yi Shen such that they have the same amount of money.

1/2 of $2 = $1

You can see this as :

Yi Shen + $1 first. So the difference between him and Xavier decreases by $1 to become to $1 only

Now Xavier - $1 because that $1 went
to Yi Shen. So the difference would decrease by another $1 to become 0.

Thanks a lot J! I appreciate you helping me understand better

You're welcome!