Question

i have puted this question 3rd time plz help me for this question step by step explanation ​

Answer 1

i. if h1/h2=v/u

1/3=5/u

u=15cm

1/f=1/v-1/u

1/f=1/5-1/15

1/f=-2/15

f=-15/2

f=-7.5