Question

plizzz varog doar cele incercuite!

Answer 1

7.

xz + yz = z · (x + y) = 15 · 23 =345

8

xz - yz = z · (x-y) = 10 · 12 =120

9

ab + ac = 420 ⇒ a · (b +c) = 420 ⇒ 14a =420⇒a= 30

10

ab - ac = 135⇒a·(b - c) =135⇒ 9· (b - c)=135⇒b-c=15