Question

1)Se stie ca:ab+ac=420 si b+c=14.Aflati a.
2)Se stie ca:ab-ac=135 si a=9.Aflati b-c

Answer 1

$1).ab+ac=420 \\ b+c=14 \\ a=? \\ ab+ac=420 \\ a(b+c)=420 \\ 14a=420 \\ a=420:14 \\ \boxed{a=30} \\ 2).ab-ac=135 \\ a=9 \\ b-c=? \\ ab-ac=135 \\ a(b-c)=135 \\ 9(b-c)=135 \\ b-c=135:9 \\ \boxed{b-c=15}$