Can someone me with the ones circled

For number 3,dissect the shape into a tiny rectangle and a huge one
tiny rectangle=1×(5-3)
=1×2
=2
big rectangle=(4-1)×5
=3×5
=15
15+2=17
17 is the area
oh it is done for you whatever
Question 4
4×3.14=12.56(whole circle)
12.56÷2=6.28(half circle)
half circle + rectangle area =total area
rectangle area
4×6=24
24+6.28=30.28