Question

$\frac{3}{12} = \frac{21}{?}$
plz answer​

Answer 1

Step-by-step explanation:

A combination reaction is a reaction where two or more elements or compounds combine to form a single compound. Such reactions are represented by equations of the following form: X + Y → XY. The combination of two or more elements to form one compound is called combination reaction.

Answer 2

Answer:

$\frac{3}{12} = \frac{21}{x} \\ x = \frac{21 \times 12}{3} = \frac{7 \times 12}{1} \\ x = 84$

that's is your answer