Hello there!
First off let's remember what a mole is. Molarity= mol/L
Next, we have to know what molarity the stomach is 0.155 Molar. I had to google this number because according to this problem you don't seem to be doing pH to molarity conversions yet.
Next, we plug into the formula watching out for units.
.155M=xmols/.010L
10.0ml -> .010L
next we use our calculator to solve this answer
.155M x .010L= .0155mol
I hope this helps!
Andrea