Find the common difference of the arithmetic sequence 20,18,16,...

Which of these choices show a pair of equivalent expressions?

Each month, a shopkeeper spends 5x + 14 dollars on rent and electricity. if he spends 3x−5 dollars on rent, how much does he spend on electricity? for which value(s) of x is the amount the shopkeeper spends on electricity less than $100? explain how you found the value(s).

Who ever answers this will get a cookie from batman