Question

a
-- = 4 ; a,b diferite de 0
b
____________________
3a-2b
Demonstrati ca --------- = 10
b

Answer 1

a/b=4
(3a-2b)/b=10
a=4b si înlocuim
(3×4b-2b)/b=(12b-2b)/b=10b/b= 10
.

Answer 2

$\displaystyle\frac{3a-2b}{b}=10\implies \frac{3a}{b}-2=10\implies \frac{3a}{b}=12 \\ \\ a=4b\implies 3a=3\cdot4b=12b \\ \\ \frac{3a}{b}=\frac{12b}{b}=12\implies \frac{3a-2b}{b}=10$