First balance the equation of the reaction:
NaOH + HCl ---> NaOH + H2O
The ratio of moles is 1:1
M1V1 = M2V2
(molarity1 x volume1) = (molarity2 x volume2)
M2 = M1V1 / V2
molarity2 = (molarity1 x volume1) / (volume2)
M of HCl = 50M x 0.025 litres / 0.02625 litres
= 47.6 M
2625 ml = 0.693451637 US gallons