Question 945424
{{{N+D=71}}}
{{{5N+10D=495}}}
From eq. 1,
{{{5N+5D=5(71)=355}}}
{{{5N=355-5D}}}
Substitute into eq. 2,
{{{355-5D+10D=495}}}
{{{5D=140}}}
{{{D=28}}
Then,
{{{N+28=71}}}
{{{N=43}}}