Answer:
$128
Step-by-step explanation:
Given: Nghiep gave half of his weekly salary to his mother.
 Spent remaining half on a new shirt.
 Finally he is left with $32
Lets assume Nghiep´s weekly earning be "x".
As given, Nghiep gave his mother half of weekly earning.
∴ Remaining earning= 

Taking LCD as 2
⇒ Remaining earning= 

Hence, remaining salary giving half earning to his mother is 

Now, as given Nghiep spent half of what was left on a new shirt.
∴ Amount spent on shirt= 

Next, finding the amount left with Nghiep after spending on shirt.
⇒ Amount left after spending on shirt= 

taking LCD as 4
⇒ Amount left after spending on shirt= 

As given, Nghiep left with $32 after spending on shirt.
∴ We can form an equation for amount left with Nghiep after spending on shirt.
⇒

Now, solving it to find the weekly earning of Nghiep.
⇒ 

Multiplying both side by 4.
⇒

∴ 

Hence, Nghiep´s weekly earning is $128.