Answer:
Luca has 55 crayons as 42 + 13 = 55
7. e and f
9. c.
sorry didn't understand 8
Answer:

Step-by-step explanation:
General equation of a parabola that opens up is
, a>0
So equation becomes
which implies option A and option B can never be true for this parabola.
Also this parabola's vertex lies in 3rd quadrant where coordinates of both x and y will be negative.
So, the equation of parabola will be of the form 
Hence, option 4 that is
is correct.
When the firecracker hits the ground, H(t) = 0.0 = -16t^2 + 90t + 160 Using the quadratic formula,t = (-90 +- sqrt(90^2 - 4(-16)(160))) / 2(-16)t = -1.42 ort = 7.04
The negative time is extraneous. Therefore,t = 7.04 s.
Seven Seconds is your answer!