Question

help me with this question
plzzz. ​

Answer 1

Answer:

40/21

Explanation:

u=20cm ,v=40cm

focus=f

1/f = 1/v+ 1/u

1/f =1/40 +1/20cm

1/f=21/40

f=40/21

Answer 2

Answer:

it's okay

please follow me and mark the brailist please