Step 1: look at the histogram

The histogram tells us that 15 people watch 2 to 4 hours of TV per week, and 21 people watch 4 to 6 hours per week, and so on.

Step 2: find the corresponding bars that are equivalent to “people who watch at least 4 hours per week”

The number of people who watch at least 4 hours per week is

$$ 21+17+19=57 $$