Question 174698
lets call the time spent at soup kitchen,trash pickup, and toy collecting
s, t, and c, respectively
:
c=4t...........eq 1
s=t-2..........eq 2
s+t+c=40.......eq 3
:
:
c=4t........eq 1
s+t+c=40....eq 3
:
multiply eq 1 by -1 to then add the two equations together thus eliminating the c terms, leaving us with s+t=-4t+40---->s+5t=40
:
s=t-2.....eq 2
s+5t=40...revised equation after eliminating c terms
:
multiply eq 2 by -1 and add the two equations together thus eliminating the s terms, leaving us with  5t=-t+2+40
:
6t=42
: 
{{{highlight(t=7)}}}hours picking up trash
:
{{{highlight(c=4t=4(7)=28)}}}hours toy collecting
:
{{{highlight(s=t-2=7-2=5)}}}hours in the soup kitchen