Hi there... I need help on a question... here goes the problem
Assume the average salary for a worker in the US is $27,500 and that the annual salaries for Americans are normally distributed with a STANDARD DEVIATION equal to $6,250. What percentage of Americans earn below $18,000?

Help with starting the problem would be great

I stand to be corrected but if I remember correctly, you should already know what percetages are covered by one, two, three SD's, etc. in all cases, and I suspect you work more or less based on that thought process.

I still don't get it

Just use the formula z=\frac{x-{\mu}}{\sigma}, then look up the corresponding value in the body of the z table.