(765-279) :6+80:16•17=? 1000-48:24•344:4=? 450:5:15•145-14•5=?

Question

(765-279) :6+80:16•17=?
1000-48:24•344:4=?
450:5:15•145-14•5=?

Answer 1

486:6+85=81+85=166
1000-172=828
870-70=800