Answer:
72
Step-by-step explanation:
Since the ratio of blue jays to robin's was 6 to 7 then if there were 84 robins how many blue jays were there.
6 to 7 can also be express as 6/7
Thus, we can set up a proportion
6/7 = x/84
Now, we have to solve for x
x = 72
Hence, if there were 84 robin there would be 72 blue jays.
~lenvy~