The starting equation is 100=S+D+K S is for Sarah, D is for Dave, and K is for Kate
This is what we know: S=15+D and K=D-5 Now that we know how to find the values of everything, we must plug it in.
100=(15+D)+D+(D-5) Combine like terms. 100=10+3D Subtract 10 to isolate variable. 90=3D Divide by 3 to isolate variable. 30=D Plug in number to find the answers.
Answer: Sarah worked for 45 hours Dave worked for 30 hours Kate worked for 25 hours
