It depends on the organisations which would receive the additional donations. If the person quitting their job is 10 % more cost-effective than the person who would replace them, donates 10 % of their gross annual salary to an organisation 10 times as cost-effective as their initial organisation, their donations doubled as a result of quitting, and there was no impact from direct work in the new organisation, their annual impact after quitting would become 1.82 (= (0 + 0.1*2*10)/​(0.1*1 + 0.1*10)) times as large as their initial annual impact.
Hi Tom,
It depends on the organisations which would receive the additional donations. If the person quitting their job is 10 % more cost-effective than the person who would replace them, donates 10 % of their gross annual salary to an organisation 10 times as cost-effective as their initial organisation, their donations doubled as a result of quitting, and there was no impact from direct work in the new organisation, their annual impact after quitting would become 1.82 (= (0 + 0.1*2*10)/​(0.1*1 + 0.1*10)) times as large as their initial annual impact.