Question 377639
1.{{{P+10D=71}}}
2.{{{P=4D+1}}}
Substitute eq. 2 into eq. 1,
{{{4D+1+10D=71}}}
{{{14D+1=71}}}
{{{14D=70}}}
{{{highlight(D=5)}}}
Then from eq. 2,
{{{P=4(5)+1}}}
{{{highlight(P=21)}}}