Giving 20 points! can someone explain to me what a proportional relationship is? and an example on how to solve it

A proportional relationship is one in which two quantities vary directly with each other. We say the variable y varies directly as x if:

y=kx

for some constant k , called the constant of proportionality .

(Some textbooks describe a proportional relationship by saying that " y varies proportionally with x " or that " y is directly proportional to x .")

This means that as x increases, y increases and as x decreases, y decreases-and that the ratio between them always stays the same.

A proportional relationship is one in which two quantities vary directly with each other. The variable y varies directly as x if y=kx. For some constant k, is also called the constant of proportionality. I hope this helps!

b. astronomers