pH of 1 means [H+] of 10^-1 = 0.1M
Hence you need a final number of HCL moles in XS to produce that 0.1M concentration
When v added is 30mL you have a total v of 55mL, and you're adding 0.055mol HCl against 0.025mol NaOH
Hence 0.03mol H+ in excess and then solve accordingly