For number 3 I don’t rlly get it

Find the values of y: 3y^3(y^2+ 2/3y)=0

Tim's phone service charges $26.39 plus an additional $0.21 for each text message sent per month. if tim's phone bill was $31.64, which equation could be used to find how many text messages, x, tim sent last month?

If g^-1(x) is the inverse of g (x) which statement must be true