You certainly can do it Hiy's way but there is an easier way.
This shape is what you in America call a Trapezoid
(we have a different name for it in Australia but I will not confuse you with that)
The area of a trapezoid = \(\frac{1}{2}* (sum \;of \;parallel\;sides\:)* perpendicular\;height\)
How long are the parallel sides?
What is the perpendicular height?
What is the area of this trapezoid?