Pls help im stuck on this

The -2/5 means we go to the left 2/5 of a full unit. So we take 2 small little steps (going over 2 little tickmarks), then we move 4 small steps to the right due to the +4/5 portion. Ultimately, we end up at 2/5 as the answer

So -2/5 + 4/5 = 2/5

This can be thought of as -2+4 = 2, then you just stick 5 in the denominator for each term.

54 km / hours

step-by-step explanation:

we need to convert seconds to hours

60 seconds = 1 minutes

60 minutes = 1hour

15 m         60 second   60 minutes

  * *         = 54000 meters/ hour

second     1 minute             1 hour

now we need to convert meters to km

1000 m = 1 km

54000 m       1 km

*   = 54 km / hours

hour               1000m