Answer:
It takes the printer 20 minutes to print a banner
Step-by-step explanation:
Notice that there are two unknowns in this problem: the time to print a poster and the time to print a banner. Let's assign the letter "b" to the time it takes to print a banner, and "p' the time it takes to print a poster.
So we can write the following two equations involving the total amount of time that takes to print in the two cases:

We can solve for the unknown "p" by subtracting term by term in the equation set above:

So it takes 10 minutes to print each poster, we can find the time it takes to print the banner by using the value we just found in one of the equations:

So, it takes 20 minutes to print a banner.
Answer:
180/7
Step-by-step explanation:
Comment if you want it, but it's very long.
Answer:
I believe he can go on 30 rides.
Step-by-step explanation:
The equation would be 5 + .5x = 20
Because $5 to get in, plus $.50 per ride (x is number of rides you are solving for), and $20 is total amount you can spend.
So, .5x=15 so x=30