Answer: 7
Explanation:
1) Set up an equation. Let x be the number of hours he works.
2) Solve the equation
(<= mean less or equal to)
400/64 <= x
6.25 <= x
3) Solve the problem
We need to round up 6.25 as 6.25 is not on the list. Since the number has to be greater than 6.25, the next option is 7.