How do I solve this quadratics problem?

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The problem:

A jet flew from Tokyo to Bangkok, a distance of 4800km. On the return trip, the speed was decreased by 200 km/h. If the difference in the times of the flights was 2 hours, what was the jet's speed from Bangkok to Tokyo?

From the problem, we can see that the variables are:

Distance:

T to B = 4800km

B to T = 4800km

Speed:

T to B = $x$km/h

B to T = $x-200$km/h

Time:

T to B = $x$h

B to T = $x-2$h

The problem definitely needs to be solved using the distance formula, $d=s*t$. Rearranging it for time, we get $t=d/s$

What do I do from here? I know from solving similar previous problems that I have to factor it and get the x-intercepts (one of them will be the jet's speed) but how to I solve up to that point when there are two unknowns?

Thank you!