7x/8 = 21

Question

i am kind of confused on this

Answer 1

I did 21 divided by 8 = 2.625

Answer 2

7x/8 = 21
7x = 168
x = 24

or,

7(x/8) = 21
x/8 = 3
x = 24

If you divided 21 by 8, you were just guessing.

Answer 3

but how do you know how to get it?