Calculating Concentration

In the question, I need to calculate concentration of two solutions.
One with 30ml of 10M metal solution(Fe 2+) and 50ml of buffer.
 Another with 10ml of 10M metal soltion (Zn 2+), 20ml of water, and 50ml of buffer.

I need to calculate the concentration of metal in both mixture.
Can anyone help me how to calculate this step by step?

I tried to calculate the concentration by multiplying the metal concentration, 10M, by the amount of metal, 30ml, but this doesn't look like concentration. Do I need to divide by total volume of solution, 80mL??

I am confused.
Please help me!!