I have no idea how to answer this

What is the solution to the system of the equations? x = y - 3 x + 3y = 13

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).

For the following geometric sequence, find the recursive formula. {-80, 20, -5, } i need : ')