<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
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Add these 2 equations together:
</span>-9x = -27 + 9y
20x= 71- 9y
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<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).
F(a)=-2a^2 - 5a^4
if a=-3
f(-3)=-2(-3)^2 - 5(-3)^4
=(-2*9) - (5*81)
=-18 - 405
=423
1. 4 3/4 feet = 19/4 feet
2 2/5 feet=12/5 feet.
multiplying them together yields


Part 2:
11.4 ft^2 - 4 1/2 ft^2=
11.4-4.5=6.9 ft^2 = 69/10 ft^2 left after you subtract the decoration in the middle
Now you're trying to find now many rectangular cutouts (that each are 3/8 ft^2) will fit in the remaining space.
You do that by dividing the remaining space left by 3/8:

since you have to have a whole number of cutouts, you round 92/5 down to 90/5, which is
18 cutouts
Answer:
They need to wash 72 cars
Step-by-step explanation:
2000 - 1640 = 360
360/5 = 72
Answer:
<em>n</em> - <em>k</em> + 1
Step-by-step explanation:
This is assuming (because you did not say) that <em>n</em> and <em>k</em> are integers and <em>n</em> is greater than <em>k</em>.
Example: from 2 to 5 {2, 3, 4, 5} includes 5 - 2 + 1 = 4 numbers.
Example: from -6 to 4 includes 4 - (-6) + 1 = 11 numbers, namely {-6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4}