Molarity= (number of moles of that substance) / (Volume of solution in litres)
7= (number of moles of HCl) / 0.05
Thus,
Number of moles of HCl = 7 x 0.05 = 0.35
The number of moles of HCl will remain unchanged.
Now, for new solution,
0.35= 0.35 / (New volume of solution in litres)
Thus,
New volume = 1 litre
Thus, amount of water added = 1- 0.05 litre = 5.0 M