a

d

b

- 1

2

( 1+20%)a

50.4 yuan/barrel

c

a

20 1 1

10+2(x-3)

14

a+2

65438+ 0 o'clock the next day

S shadow = A2+B2+1/2 (a-b) xb-1/2a2-1/2 (a+b) xb.

When a = 5cm and b = 3cm, S shadow = =12.5cm 22.

(Square indicated by 2)

Integral expression

and

Merge category items

I can't tell you the answer because I haven't done my homework yet.