Answer: 2
Step-by-step explanation:
A pond had 60 fish but 10 were added so now the pond has 70 fish.
The probability of choosing a carp is 1/2 so
= 35 are now carp.
There were 27 carp and now there are 35 carp so 8 carp were added.
10 fish were added and 8 of them were carp so 2 of them were tench.