Question 11Find the area of the shown room, whose adjacent walls are perpendicular and dimensions are marked $a , b$. $2 ab + a \left(b - a\right)$$3 a \left(a + b\right) - a^{2}$$3 a \left(b - a\right) + a^{2}$$3 ab$$2 \left(a^{2} + ab\right)$
