On a sunny day mark can stay in the sun for 20 minutes before he gets sunburnt. he wants to sunbathe for 3 hours. what is the lowest level of sun protection that he should use : 5, 15, 20, 30, 50
also the question below

For the 1st question, 30. Not too high, not too low. 
2nd one is Their bodies are used to it and it's the way they were made, so lets say a (NOT BEING RACIST) let's say a white person and a Latino, went out, the white would have a greater risk because their bodies aren't used to the sun more than the Latino! 

Bhope this : )