How long does it take to get from earth to mars at a speed of 40000 miles per hour?

Earth is approx 93 million miles from the sun

Mars is approx 142 million miles from the sun

If you time your journey so that the shortest possible journey is made, that is when Mars and Earth are on the same side of the sun, the distance travelled is approx 142 - 93 = 49 million miles which at 40000 mph would take (49 x 106) ÷ 40000 hours = 1225 hours or about 51 days.

If you time your journey so that the longest possible straight line journey is made, that is when Mars and Earth are on opposite sides of the sun (with a trip through the sun), the distance travelled is appox 142 + 93 = 235 million miles which at 40000 mph would take (235 x 106) ÷ 40000 hours = 5875 hours or about 245 days.*

So the journey from Earth to Mars at 40000 mph would take somewhere between approx 1225 hours (51 days) and approx 5875 hours (245 days).

*Obviously you can't go through the sun, but this also assumes that the sun has no diameter - it's diameter is approx 0.8 million miles, adding an extra 21 hours or nearly a day.