Please help with question

An equation of the line tangent to y=x^3+3x^2+2 at its point of inflection is

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).

Aline passes through 3,7 and 6,9 what equation represents the line