C) (0.85 + x/100)(250+145) does not give the correct answer.
Explanation
A) works; adding the two costs together is 250+145=395. We multiply this by 0.85 because 100%-15%=85%=0.85. We also have x% tax, which is represented by x/100, added to 100% of the value, or 1.00. Altogether this gives us
395(0.85)(1+x/100) = 395(0.85 + (0.85x/100)) = 395(0.85) + 395(0.85x/100)
= 395(0.85) + 395(0.0085x)
B) works; we have 250+145 for the original price; we have 85% = 0.85 of the value; we also have 100% + x%, which is (100+x)/100.
C) does not work; (0.85+x/100)(395) does not take into consideration that you are finding the tax after taking the 85%. This will simplify out to
0.85*395 + (x/100)(395) = 335.75 + 395x/100 = 335.75 + 3.95x, which is too much.
D) works; simplifying the expression from A, we have 395(0.85) + 395(0.0085x) = 335.75 + 3.3575x.
Using a system of equations, it is found that Gina got 22 questions correct in the test.
<h3>What is a system of equations?</h3>
A system of equations is when two or more variables are related, and equations are built to find the values of each variable.
In this problem, the variables are:
- Variable x: Number of questions she got correct.
- Variable y: Number of questions she got wrong.
The test has 30 questions, hence:
x + y = 30 -> y = 30 - x.
She scored 152 points, hence, considering the value of each question:
8x - 3y = 152.
Since y = 30 - x:
8x - 3(30 - x) = 152
11x = 242
x = 242/11
x = 22
Gina got 22 questions correct in the test.
More can be learned about a system of equations at brainly.com/question/24342899
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9514 1404 393
Answer:
A. no
B. no
C. obtuse
Step-by-step explanation:
For side lengths to form a triangle, the sum of the shorter two must exceed the longest.
A. 5 + 8 = 13 . . . . a line segment, not a triangle
B. 7 + 12 < 26 . . . . no closure, not a triangle
C. 11 + 15 > 20 . . . . a triangle. A picture shows it to be obtuse
You can also compare 11² +15² vs 20² ⇒ 346 vs 400. The long side is too long for a right triangle, so the triangle must be obtuse. (The Pythagorean theorem tells you a right triangle with those legs would have a long side of √346 = 18.6.)
It started at $37.
It went down $3.
37 - 3 = 34
It went up 1.
34 + 1 = 35
It went down 7.
35 - 7 = 28
It went up 4.
28 + 4 = 32
The price at the end of the day was $32.
The charge per unit of electricity is #415
The formula for E in terms of N is E = 375 + 40N
<h3>What is variation?</h3>
Variation is a mathematical term that establishes the relationship between quantities and variables in an equation.
Analysis:
E = K + CN
where K and C are constants
When E = 3655, N = 82 and when E = 2055, N = 42
3655 = K + 82C ---------------1
2055 = K + 42C----------------2
subtract equation 2 from 1
40C = 1600
C = 40
substitute C in equation 1
3655 = K + 82(40)
3655 = K + 3280
K = 3655 - 3280 = 375
charge per unit is N = 1
E = 375 + 40(1) = #415
Formula for E in terms of N is E = 375 + 40N
In conclusion, the charge per unit of electricity is 415 and the equation connecting E and N is E = 375 + 40N
Learn more about Variation: brainly.com/question/6499629
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