Problem Solving

My English course is split into four components; a paper test (a), an online test (b), an essay (c) and an exam (d). (a) is worth 30% of my final grade, (b) is worth 10%, (c) is worth 10% and (d) is worth 50%. The grading system for each component is marked out of 22. I have received my individual grades for (a) (b) and (c). They were 16, 22 and 19 respectively. My exam is tomorrow. In order to pass the course, I need to obtain at the very least 9/22 overall. Given the grades I have already received, what is the minimum mark I need to obtain in the exam itself?
(A) 0.1
(B) 0.2
(C) 0.5
(D) 1.0
(E) 1.2

Let a be the required grade in exam.

(30*16 + 10*22 + 10*19 + 50a) / 100 = 9

a = 0.2

Answer: B