Question 304033
{{{P+11=(1/2)(P-13)^2}}}
{{{P+11=(1/2)(P^2-26p+169)}}}
{{{2(P+11)=(1/2)(2)(P^2-26p+169)}}}
{{{2P+22=P^2-26p+169}}}
{{{0=P^2-28p+147}}} -7 and -21
{{{(P-7)(P-21)=0}}}
{{{P=7}}},{{{21}}} cant be 7 as 13 years from 7 is negative
so peter is {{{highlight(21)}}}
checking
{{{21+11=32}}}
{{{32=(1/2)(21-13)^2}}}
{{{32=(1/2)(8)^2}}}
{{{32=(1/2)64}}}
{{{32=32}}}
correct