Question 1122463
c children
e students
a adults


{{{a/2=(c+e)}}}-----half as many adults as sum of students & children


{{{a=2c+2e}}}


{{{system(c+e+a=1050,3c+5e+7a=5150)}}}


{{{c+e+2c+2e=1050}}}
{{{3c+3e=1050}}}
{{{c+e=350}}}


{{{3c+5e+7(2c+2e)=5150}}}
{{{17c+19e=5150}}}


Revised simplified system in TWO variables:
{{{system(c+e=350,17c+19e=5150)}}}, and remember {{{a=2e+2c}}}.