project can be completed in 10 days by A alone, 12 days by B alone, and 15 days by C alone, now B and C will do 2 days first, and A will do the rest, how many days will it take?
一件工程，甲独做10天完工，乙独做12天完工，丙独做15天完工，现由乙、丙先做2天，余下的由甲独做，还需多少天？
<result>10</result>