I need help please. Find the x and y for me please

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).

Solve this equation using substitution. {4x + y = −2} {4x + 6y = 44}

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base