pretend the cost of the hotel is called "x" and the amusement park is "y"
make the equations.
450=3x+2y and 700=5x+3y
since you're solving for amusement park, you basically just solve for y
multiply the first equation by 5 and the second equation by 3.
2250=15x+10y and 2100=15x+9y
these are a system of equations so subtract one from the other to cancel the x values away.
150=y so the answer is that a day trip to the amusement park costs $150