Calculate the value of b in the graph using algebra: Y= 6.5cos(bx)

If the graph goes through (6.5,0) and (17.7,4.9)

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).

Hi, can anyone show me how to do this problem? 100 points for this. in advance

2. explain in words how you plot the point (4, −2) in a rectangular coordinate system.