Answer:
let's divide the figure into the two parts.
surface area of cuboid=2(lb+bh+hl)
surface area of cuboid=2(12×4+4×6+6×12)
surface area of cuboid = 288 unit²
diameter of cylinder =4
radius=4/2
surface area of half cylinder= pi×r(h+r)
surface area of half cylinder=3.14×2×(12+2)
surface area of half cylinder=87.92 unit²
surface area of figure=288 unit²+ 87.92 unit²
surface area of figure = 375.92 unit²