Respuesta :

that is true

Step-by-step explanation:

3×3x = 9x

3×7= 21

So 9x + 21

because you cant add a variable to a number that doesnt have the same variablem

Answer:

All real numbers make this equation true, so it is true.

Step-by-step explanation:

3(3x+7)=9x+21 if I were to input 3 as x on both sides, it would equal 48 on each side.

It essentially becomes 3(9+7)=27+21

then 3(16)=48

48+48

This is true for all variables, so the equation must be true