Thank you for the opportunity to help you with your question!

What you need to do is cross multiply. This means multiply the numerator of one side with the denominator of the other side of the equation and set it equal to the other set of numerator times denominator.

In this case it means multiply 16 with r and 30 and 8.

So...

16r=30*8

16r=240 Divide both sides by 16

r=15

Please let me know if you need any clarification. I'm always happy to answer your questions.