What you should keep in mind in this case is that you have an absolute value function.
You must replace x = -10 in the equation.
We have then:
b (x) = lx + 4l
b (-10) = l-10 + 4l
b (-10) = l-6l
b (-10) = 6
Answer:
The function evaluated at x = -10 is:
b (-10) = 6