`1/5` of `90=`

What will come in the place of question mark (?) in the following questions ? 5/6" of "2""1/3" of "90%" of "420=?

Find the ratio of 90cm to 1.5m

Find the ratio of 90 cm to 1.5 m.

Find the ratio of 90 cm to 1.5 m.

A printed page is kept pressed by a glass cube (µ=1.5) of edge 9.0 cm. By what amount will the printed letters appear to be shifted when viewed from the top?

A printed page is kept pressed by a glass cube (µ=1.5) of edge 9.0 cm. By what amount will the printed letters appear to be shifted when viewed from the top?

What happens when 2.4% of chromium, 1.5% of carbon and 90-95% of iron combine together?

What is the value of ([tan(90-theta)+sec(90-theta)-1])/([tan(90-theta)-sec(90-theta)+1]) ?

Prove that : (1)/ (1 + cos (90^(@) - A)) + (1)/ (1 - cos (90^(@) - A)) = 2 cosec^(2) (90^(@) - A)

Show that (1)/( 1 + cos (90^(@) - theta)) + (1)/(1 - cos (90^(@) - theta )) = 2 cosec ^(2) (90 ^(@) - theta )