Question 1124163
----
The sum of Pete's and Sam's ages is 30. Five years ago, Pete was 3 times as old as Sam. How old is Sam? 
----


{{{system(P+S=30,P-5=3(S-5))}}}


{{{P-5=3S-15}}}

{{{30-S-5=3S-15}}}

{{{25-S=3S-15}}}

{{{25=4S-15}}}

{{{4S=25+15=40}}}

{{{highlight(S=10)}}}