Hey there I am just telling you , it seems that your questions is incomplete . Can you kindly post the whole question then I am able to solve it.
please don't mind.

If I understood correctly and didn't make any mistakes...
Answer: a) 0.7
b) 70%
Step-by-step explanation:
a) There are 10 marbles.The red marbles are 7
so that 7/10
then change to decimal 7/10=0.7
b) if we get percentage *100
so, 7÷10*100%
70%
It will take Carlos 4 hours to walk 16 miles.