Question

Aflati-l pe a din proportia:

Answer 1

$\frac{30}{1}=\frac{a}{4}\\30*4=a*1\\a=120\\Formula:\\\frac{a}{b}=\frac{c}{d}\\ad=bc$

Answer 2

30x4=1xa 120=a sau a= _30x4__=120 1