No it’s not a jelly or a jam
You can write a system of equations, I'm pretty sure.
the first equation would be
10a+3f+.5c=100
and
a+f+c=100
For the first equation, its the price of each ticket that adds up to 100 tickets
For the second equation, its the amount of people that adds up to 100 people.
I'm pretty sure this is the route to go but I haven't solved it for myself (yet) I'll probably comment the answer if you need me to
5x + 50 +x
= 5x*2( square ) + 50
Isolate the variable by dividing each side by factors that don't contain the variable.
f=e-g/d
I'd do 9x4=36 because the 9 is from your money and the 4 is from your books. Now since you want to find out how much 4 books cost you just multiply that by 9