Ratios are kind of like fractions, you can divide them (unless they are in their simplest form) or you can multiply them. In this case, this ratio is in its simplest form and cannot be divided.
So let's multiply!
7 x 2 = 14
84 x 2 = 168
One ratio equivalent to 7:84 is 14:168
You can multiply it even more if you'd like.