Mara and Riley went to a carnival, Mara rode the bumper car two times, Riley rode the space shuttle four times, and they both rode the Ferris wheel three times. If a ticket for a bumper car cost $2, a ticket for a space shuttle cost $4, and a ticket for a Ferris wheel cost $5, how much money did they spend?
Thoughts? Step-by-step reasoning:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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Mara spent $2 x 2 = $4 for riding the bumper car two times. Riley spent $4 x 4 = $16 for riding the space shuttle 4 times. They spent $5 x 3 = $15 each riding the Ferris wheel 3 times. So, they spent a total of $15 x 2 = $30 riding the Ferris wheel. Therefore the total amount they spent at the carnival is $4 + $16 + $30 = $50.
Thus, the answer is 50.