First step is to convert it from molarity to moles and we can do that since we're given both the molarity and the volume.
1.50M NaCl * 6.00L = 9mol NaCl
Next, we determine the molar mass of NaCl (use the periodic table)
Na = 22.98977g/mol Cl = 35.453g/mol
NaCl = 22.98977g/mol + 35.453g/mol...