Three siblings date kate and sarah spent 100 hours habitat for humanity build new housing .sarah worked 15 hours more than dave. kate worked five few hours then dave. how many hours each of the siblings volunteer?

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.

Sarah worked for 45 hours
Dave worked for 30 hours
Kate worked for 25 hours

I think it’s 10 I don’t know I try I’m in 5th grade

Yes, two vertical lines can be complementary