10 mL of 1 N HCl is mixed with 20 mL of 1 M ${\mathrm{H}}_2{\mathrm{SO}}_4$ and 30 mL of 1 MN a OH. The resultant solution has:

The moles in the resultant solution can be calculated as,

$n_{{\mathrm{H}}^{+}}=[10\times 1+20\times 1\times 2-30\times 1]=20$

Hence, the resultant solution has $20\text{ meq of }{\mathrm{H}}^{+}\text{ions }$.