What is the vertex of y=-3x^2+90x-675
and y= -3(x-15)^2

If m∠abc = 70°, what is m∠abd? justify your reasoning.  using the addition property of equality, 40 + 70 = 110, so m∠abd = 110°.  using the subtraction property of equality, 70 − 30 = 40, so m∠abd = 30°.  using the angle addition postulate, 40 + m∠abd = 70. so, m∠abd = 30° using the subtraction property of equality.  using the angle addition postulate, 40 + 70 = m∠abd. so, m∠abd = 110° using the addition property of equality.

If value of cos330° is √3/2 then find tan165°.

Hey hotel charges guests $19.75 a day to rent five video games at this rate which expression can be used to determine the charge for renting nine video games for one day at this hotel? pls