If an arrow is shot upward on mars with a speed of 68 m/s, its height in meters t seconds later is given by
y = 68t − 1.86t2.
(round your answers to two decimal places.)
(a) find the average speed over the given time intervals.
(b) estimate the speed when t = 1.

b. would be the answer : )

step-by-step explanation:

step 1: add -16x to both sides.

16x−4y+−16x=64+−16x  

−4y=−16x+64

step 2: divide both sides by -4.

−4y /-4 = -16x + 64/-4

answer:   y=4x−16

hope i'm right

c.

step-by-step explanation:

a reflection across the x axis and a 90 degree rotation left and right.

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.