The answer is -3. Adding a negative onto a positive is just like subtracting from the positive. So, first off, 5+(-3) is 2. Then, subtracting 6 from the 2 will give you a negative number, -4. Subtracting a negative changes the sign to be a plus, so you plus one onto the -4. This leaves you with the answer of -3.
P(LC / S) = P(S intersect LC) / P(S)
P(S intersect LC) = P(S)*P(LC / S) = 0.19 * 0.158 = 0.03
It would be: 11 * 90/100
= 11 * 0.90 = 9.9
So, your final answer is 9.9
Hope this helps!
Answer is D) Y. It's matching with the results given