In a zoo there are 17 more monkeys than lions and 30 more lizards than lions. If there were 151 monkeys, lions and lizards in total, how many of each kind are there?

If the amount of monkeys is m, lions is a, and lizards is b, then a+b+m=151, 17+a=m (since there are 17 more monkeys than lions), and 30+a=b. Substituting those values in (17+a=m and 30+a=b), we have 30+17+a+a+a=151=47+3a. Subtracting 47 from both sides, we get 104=3a. Next, we can divide both sides by 3 to get 104/3=a (the number of lions), 104/3+17=the number of monkeys, and 104/3+30=the number of lizards. Somehow we end up with a fraction (not a whole number), so there are 2/3rds of monkeys floating around using this logic.