monomethylamine aqueous solution

Given (Credits to @G.Patton) 6.2g methylamine in 35mL water (prepared by adding a solution of 7.9g (198mmol) sodium hydroxide in 20mL cold water to a cooled solution of 13.5g methylamine HCl in 15mL water). This results in an 15% methylamine solution. We want to scale this to yield a 21%...

I cannot seem to find the correct way to convert methylamine hydrochloride to a 40% aqaous solution. If you are the one who knows how to do it, sharing your knowledge would be really appreciated.