Answer:
Bo's original paycheck is $3000.
Explanation:
Bo paid bills with 1/2 of his paycheck and put 1/5 of the remainder in savings. 
The rest of his paycheck he divided equally among the college accounts of his 3 children.
Let his earnings be x
So, 
 went in bills.
went in bills.
And he put 1/5 of the remainder in savings. 

He put 
 of x in savings
 of x in savings
Adding the bill and remainder amount = 

= 

So, left amount was = 

This 2/5 was divided equally among 3 kids making it : 

Now, as given, Bo deposited $400 in 3 kids accounts. This gives 
 in total in kids account.
 in total in kids account.
We know $1200 is 2/5 of total income or x
So, 


x = $3000
Hence, Bo's original paycheck is $3000.