Answer:
Step-by-step explanation:

Well, it would help if you added a picture of some sorts.
It is a right triangle so,
a² + b² = x²
9² + 12² = x²
225 = x²
√225 = x
15 = x
Hope this helps :)
Answer:
Calcium carbonate reacts w/stomach acid according to the following chemical equation.
CaCO3+2HCl(aq)-> CaCl2(aq)+H2O(l)+CO2(g)