A lens of focal length 25.0 cm forms an image 37.5 cm from the lens. What was the object distance?

it can be 15 or 75

Explanation:

using this equation

f = focal length

so = object distance

si = image distance

since we do not now what lens used, I assume from the problem the lens are positive (convex) but I don't know the image position because lens have two side.

1. the positif lens with negative image distance (it means object and image are in the same side of lens)

1/25 = 1/so - 1/37.5

1/so = 1/25 + 1/37.5 = 1/15

so = 15 cm in front of the lens (same side with the image)

2. the positif lens with positive image distance (it means object and image are not in the same side of lens)

1/25 = 1/so + 1/37.5

1/so = 1/25 - 1/37.5 = 1/75

so = 75 cm in front of the lens (not in the same side with the image)

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.