Choose all that apply. Refraction telescopes: are used to pick up the faintest objects in the sky
have small lengths compared to other telescopes
are used when image quality is important
require less maintenance
are used by professional astronomers

sorry

i do knot know this

2018 means 2018 ce or common era

there have been other eras too including bce, which included way more years.

the fraction 18/22 is equivalent to 9/11.

in decimal form if needed

this is a proper fraction once the absolute value of the top number or numerator (18) is smaller than the absolute value of the bottom number or denomintor (22).

the fraction 18/22 is equal to 18÷22 and can also be expressed in decimal form as 0.818182.