Answer:
I'm not sure if there is enough information here. If you are asking how many books or bookmarks she can buy, you'll need a total amount of money :).
Because it can't be simplified.
There aren't like terms and there isn't fractions.
lions = x
monkeys = 3x ( 3 times as many )
3x +x = 24
4x = 24
x = 24/4
x = 6
6 lions
6*3 = 18 monkeys
