According to the condition in the question: b 1+b2=4cm, then there is h=b2=b 1=a=2cm.

So the shaded area = (a+b1+B2)/2 * h-1/4 π h * h = (2+2+2)/2 * 2-0.25 * 3.14 * 2 * 2, and the rest.

Question 6: If container A pours out water container B with the height of hcm, there is an equation:

48-h=(30*20*h)/(40*30)，h=32cm

Then this is the height of water in container A H=48-32= 16cm.

The fifth question, I feel lack of conditions. . .