90 x 0.4 = 36
90 - 36 = 54
The sale price is $54
The correct option is: B. 
<u><em>Explanation</em></u>
<u>The general form of growth equation</u> is:
, where A = final amount, P = initial amount, r = growth rate in decimal form and t = time duration
Here, the speed of the rocket at the beginning was 5,000 kilometers per hour and at the end will be 25,000 kilometers per hour. The speed increases at a rate of 4.3% per minute.
That means, 
Now <u>plugging these values into the above equation</u>, we will get......

So, the equation that could be used to determine the time for the speed of the rocket to reach 25,000 kilometers per hour will be: 
150 minutes / day for a week
= (150 minutes / day) * (7 days / week)
= 150 * 7 minutes / week
= 1050 minutes / week
(1050 minutes / week) * (1 hour / 60 minutes)
= (1050 / 60) hours / week
= (105 / 6) hours / week
= 17.5 hours / week
You could also convert to hours first. 150 minutes = 2.5 hours * 7 days = 17.5 hours per week.
B) In y = 25x, the value of y is 25 times the value of x, and in y = x + 25, the value of y is 25 more than the value of x.
Out of all the answer choices, b makes the most sense.
25x can be translated as 25 times x.
x + 25 can be translated as 25 more than a number.
Hope this helps!