<span>Solve the system
9x = 27-9y
20x=71-9y
Let's use the "elimination through addition/subtraction method.
Multiply the first equation by -1 so as to obtain +9y:
-9x = -27 + 9y
</span><span>20x= 71- 9y
--------------------
Add these 2 equations together:
</span>-9x = -27 + 9y
20x= 71- 9y
--------------------
<span> 11x = 44
Solve this for x: x = 44/11 = 4.
Now find y by subst. 4 for x in either of the original equations.
Using the second equation: </span><span>
</span>20x=71-9y
20(4) = 71 - 9y
80-71 = -9y
9 = -9y. Then y = -1.
The solution set is (4,-1).
Answer:
The correct answer is: 360.
Explanation:
First we can express 120 as follows:
2 * 2 * 2 * 3 * 5 = 120
You can get the above multiples as follows:
120/2 = 60
60/2 =30
30/2 = 15
15/3 = 5 (Since 15 cannot be divisible by 2, so we move to the next number)
5/5 = 1
Take all the terms in the denominator for 120, you would get: 2 * 2 * 2 * 3 * 5 --- (1)
Second we can express 360 as follows:
360/2 = 180
180/2 = 90
90/2 =45
45/3 = 15 (Since 45 cannot be divisible by 2, so we move to the next number)
15/3 = 5
5/5 = 1
Take all the terms in the denominator for 360, you would get: 2 * 2 * 2 * 3 * 3 * 5 --- (2)
Now in (1) and (2) consider the common terms once and multiple that with the remaining:
2*2*2*3*5 = Common between the two
3 = Remaining
Hence (2*2*2*3*5) * (3) = 360 = LCM (answer)
Answer:
Step-by-step explanation:
This is a differential equation problem most easily solved with an exponential decay equation of the form
. We know that the initial amount of salt in the tank is 28 pounds, so
C = 28. Now we just need to find k.
The concentration of salt changes as the pure water flows in and the salt water flows out. So the change in concentration, where y is the concentration of salt in the tank, is 
. Thus, the change in the concentration of salt is found in
inflow of salt - outflow of salt
Pure water, what is flowing into the tank, has no salt in it at all; and since we don't know how much salt is leaving (our unknown, basically), the outflow at 3 gal/min is 3 times the amount of salt leaving out of the 400 gallons of salt water at time t:
Therefore,
or just
and in terms of time,
Thus, our equation is
and filling in 16 for the number of minutes in t:
y = 24.834 pounds of salt
Answer:
You can expect at least 9 of her postcards to arrive within a week
To find that, we multiply the number of postcards by the probability
15 x 0.62 = 9.3
Hope this helps
Good Luck
