Which is a flat surface with no thickness that contains many lines and extends without end in the directions of all its lines?

A plane

This needs to be 20 characters long so this is ok

i think it is

step-by-step explanation:

a formal letter is a letter the you would send to a king

the inequality is:

250c+180g≥950

step-by-step explanation:

let c denotes the number of days in a week   miyoko worked as a cryptographer.

and g denotes the number of days in a week she works as a geologist.

now we are given that she earns $250 for every day she works as a cryptographer,and earns $180 for every day she works as a geologist.

now miyoko's goal is to earn more than $950 this week.

hence, the inequality could be represented as:

250c+180g≥950