If Jonathan went skateboarding from 4:00 PM to 4:30 PM and traveled 450 meters, what was his average speed? ​

The answer for #3 is c but i don't know why

Using the thermodynamic information in the aleks data tab, calculate the standard reaction free energy of the following chemical reaction: →+p4o10s6h2ol4h3po4s round your answer to zero decimal places.

Which of these statements best explains why space exploration should be encouraged? it prepares humans to live without oxygen. it dispel myths about objects in space. it prevents comets and asteroids from striking earth. it creates technology to absorb harmful radiations in space.