A roller coaster sitting at rest has gravitational potential energy of 289,000 J at the top of the hill. At the bottom of the hill (h = 0), its velocity is 25 m/s. What is its mass? Ignore air resistance and friction. SOLVED! (By myself)

Let's recall the formula for kinetic energy
Kinetic Energy = .5 (mass * velocity^2)

Now, while remembering PEMDAS let's plug it in
289,000 = .5 (mass * 25^2)

Let's now apply the exponent first, then multiply by the .5: Remember that you also have to multiply the mass by the same .5
25^2 = 625
289,000 = .5(mass * 625)
.5 * mass = .5m
.5 * 625 = 312.5

Now let's move all numbers except the mass variabe over to one side by dividing.
289,000/312.5 = 924.8

We're almost done here! We now need to make sure that the mass is one unit
924.8 = .5m
.5m * 2 = m

Do the same to the number!
924.8 *2 = 1849.6

1,849.6 is the answer!