Answer:
y=-30x+450
if she reads 30 pages every day it will take 15 days
Answer: the rate of the jet in still air is 685 mph and the rate of the jetstream is 75 mph
Step-by-step explanation:
Let x represent the rate of the jet in still air.
Let y represent the rate of the jet jetstream.
Distance = speed × time
Flying against the jetstream, a jet travels 3050 miles in 5 hours. This means that the total speed of the jet would be (x - y) mph. Therefore,
3050 = 5(x - y)
3050/5 = x - y
x - y = 610 - - - - - - - - - - - - - -1
Flying with the jetstream, the same jet travels 3800 miles in 4 hours. This means that the total speed of the jet would be (x + y) mph. Therefore,
3800 = 4(x + y)
3800/5 = x + y
x + y = 760 - - - - - - - - - - - - - -2
Adding equation 1 to equation 2, it becomes
2x = 1370
x = 1370/2 = 685mph
Substituting x = 685 into equation 1, it becomes
685 - y = 610
y = 685 - 610 = 75mph
1 milliliter = 0.001 liters
400 milliliters = 0.4 liters
Therefore, 4 liters is greater than 400 milliliters
The answer is actually choice A
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If we add up the equations straight down we will have 0a+2b = 6
Note how adding the 'a' terms gives us 3a + (-3a) = 3a-3a = 0a. The 0a term is really 0 since 0 times anything is 0. So the 'a' terms will go away
The equation 0a+2b = 6 turns into 0+2b = 6 and that simplifies to 2b = 6
To isolate b, we divide both sides by 2
2b = 6
2b/2 = 6/2
b = 3
We can stop here since only one answer choice has b = 3, which is choice A. However, let's keep going to find the value of 'a'
Plug b = 3 into any equation with 'a' and 'b', then solve for 'a'
3a+4b = 9
3a+4*3 = 9
3a+12 = 9
3a+12-12 = 9-12
3a = -3
3a/3 = -3/3
a = -1
So a = -1 and b = 3 pair up to form (a,b) = (-1,3)
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To check, plug this ordered pair back into both equations
Equation 1:
3a+4b = 9
3*(-1)+4*3 = 9
-3+12 = 9
9 = 9
Equation 1 has been checked out
Equation 2:
-3a-2b = -3
-3(-1)-2(3) = -3
3 - 6 = -3
-3 = -3
this is true as well
So this confirms that the final answer is choice A