Answer
SpongeBob:$64000
Patrick:$40000
Mr.Krabs:$136000
Step-by-step explanation:
8+5+17=30
Spongebob=(8/30)*$240000=$64000
Patrick=(5/30)*$240000=$40000
Mr.Krabs=(17/30)*$240000=$136000
Let
x---------> represents Martin's sister's age
y--------> represents Martin's age
we know that
--------> equation 
--------> equation 
Substitute equation
in equation 
![x+[x-6]\leq 22\\2x\leq 22+6\\ x\leq 14](https://tex.z-dn.net/?f=%20x%2B%5Bx-6%5D%5Cleq%2022%5C%5C2x%5Cleq%2022%2B6%5C%5C%20x%5Cleq%2014)
therefore
<u>the answer is</u>
Part a) An inequality that can be used to represent this situation is
or 
Part b) the oldest age Martin's sister can be is
years old
It is the same as what you had said and so a rational number is the same thing as a rational number and nothing changes.