Answer:
$900
Explanation:
Let the fixed salary be x and the commission be y, then as per given, the earnings:
- 10000y + x = 1350
 - 15000y + x = 1575
 
Subtract the first equation from the second:
- 15000y - 10000y = 1575 -1350
 - 5000y = 225
 
then 
- 10000y =2*5000y = 2*225 = 450
 
Using the first equation:
So the fixed salary is $900