The height of an object dropped from the top of a 144 foot- building is given by h(t)= -16 square +144. How long will it take the object to hit the ground?

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?

Solve the system of equations y= 3/2 - 1, -x+ y =-3

Can someone tell me if this is perpendicular? !