In simpler terms, a proton and neutron weigh 1 amu (atomic mass unit) each.
The nucleus has 15 protons and 18 neutrons. Since a proton's and a neutron's weight is only 1 amu, we can simply add the number of protons and neutrons to find the total mass of the nucleus:

The nucleus' mass is 33 amu.
Answer:
the answer is A have a nice day hope I helped
Answer:
Heat is a source of energy
Explanation:
Just took the test
Answer: Economic models<em><u> </u></em><u><em>are simplifications of reality, and in this respect economic models are no different from other scientific models.</em></u>
These are abstract idea corresponding to processes set in an economy, these are usually denoted by variables and quantitative relationships between them. These are a simplified, often numerical, hypothesis studied to elaborate convoluted processes.
<u><em>Therefore the correct option is (c)</em></u>