Question 758166
Sarah = x hrs
Kate = (x + 5)hrs
Dave = (x - 10)hrs
Add the 3 equations up.
x + (x + 5) + (x - 10) = 175
              3x - 5 = 175
                   3x = 180
                    x = 60
Sarah worked 60 hrs.
Kate worked  65 hrs.
Dave worked  50 hrs.
        Total 175 hrs.
Hope this helps.
:-)