Question

Urgent cine ma ajuta la aceste 4 ex .
1.Se stie ca : x+y=23 si z = 15. calculati xz+yz.
2.Se stie ca: x-y=12 si z = 10.calculati xz-yz.
3.Se stie ca : ab+ac=420 si b+c=14/ Aflati a
4. Se stie ca: ab-ac=135 si a = 9 /aflati b-c

Answer 1

1. xz+yz= z(x+y)= 15*23=345
2. xz-yz= z(x-y) = 10*12= 120
3. a= (ab+ac):(b+c)=420:14=30
4. b-c=(ab-ac) :a= 135:9=15