The gold number of a protective colloid is the mass in mg that just protects $10\mathrm{mL}$ of a standard gold sol from coagulation by electrolyte. Protective colloid P has a gold number of $0.025$ and colloid Q has $0.40$. A mixture containing $3.5\mathrm{mg}$ of P and $5.0\mathrm{mg}$ of Q is used; assume their protective effects are additive. What volume of the standard sol, in mL, can be protected? Give the nearest integer.

Numerical answer type, answer in mL, tolerance 1.