By titration it is found that 38.1 ml of 0.147 m naoh(aq) is needed to neutralize 25.0 ml of hcl(aq). calculate the concentration of the hcl solution.

You must know what reaction happens during titration:

HCl + NaOH --> NaCl + H₂O

So, the ratio for HCl to NaOH is 1:1.

The solution is as follows:

Concentration of HCl = Moles HCl/L solution
Concentration = (0.147 M NaOH)(0.0381 L)(1mol HCl/1 mol NaOH)/0.025 L
Concentration = 0.224 M HCl