Using activity coefficients, calculate the $pH$ in a $1L$ solution with $1\mathrm{.}355g$ of NaCl and $0\mathrm{.}640g$ of CaCl $2$

$\backslash$table$[[\frac{\text{N}\text{a}\text{C}\text{l}\text{:}}{FW},58\mathrm{.}44],[CaC{l}_2$:$,110\mathrm{.}98]]$