Given that x=2,find the value of y and z for the simultaneous equation x-2y+z=7​

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?

Is it greater than or less than7*3_9*2

In which direction does the left side of the graph of this function point? f(x) = 3x3 - x2 + 4x - 2