For 12/15=47/50, we multiply 12/15 by (1/3)/(1/3) to get 4/5. For 47/50, we multiply it by (1/10)/(1/10) to get the same denominator and 4/7/5. They are not equal.
For 16/36 and 12/27, we'll notice that 36 and 27 are both multiples of 9, so we need to get that as the denominator! Multiply 16/36 by (1/4)/(1/4) because 9 goes into 36 4 times and 12/27 by (1/3)/(1/3) due to that 27 goes into 9 3 times, we get 4/9=4/9 - these are equal!
I challenge you to get the rest of them on your own using my techniques!