There are 56 birds. And there are 10 less than twice the number of rabbits
let rabbits = r
2r - 10 = 56
Note the equal sign. What you do to one side, you do to the other. Do the opposite of PEMDAS. Isolate the r.
add 10 to both sides
2r - 10 (+10) = 56 (+10)
2r = 66
Divide 2 from both sides
2r/2 = 66/2
r = 33
33 is your answer
hope this helps