Question

Daca a x b = 18
c x a= 10
calculeaza a x (b + c): 7
a x (b - c)

Answer 1

$a \cdot b=18 \\ a \cdot c=10 \\ \Rightarrow a \cdot b +a \cdot c=18+10 \\ \Rightarrow a(b+c)=28 \\ a (b+c):7=28:7 \\ \Rightarrow \boxed{a(b+c):7=\boxed{4}}. \\ a(b-c)=a \cdot b-a \cdot c \\ \Rightarrow a(b-c)=18-10 \\ \Rightarrow \boxed{a(b-c)=\boxed{8}}.$

Answer 2

a. a·b+a·c/7
⇒18+10/7=28/7=4;
b. a·b-a·c
⇒18-10
⇒8;