1.) The sum(addition) of 21 and 5 times(multiplication) a number f is(=) 61.
f = unknown number/variable [So 21 plus 5f(5 times f) equals 61]
21 + 5f = 61 [21(one-time) + 5f(number x variable) = 61(total)]
2.) Seventeen more(addition) than seven times(multiplication) a number j is(=) 87.
j = unknown number/variable [So 17 plus 7j(7 times j) equals 87]
17 + 7j = 87
3.) n = number of calls
18 + 0.05n = 50.50
[Company charges $18 plus five cents per call(n), and the total charge was $50.50]
4.) s = the number of students
40 + 30s = 220
[Tutor charges $40 plus $30 per student(s), and the total charge was $220]
Answer: 
Step-by-step explanation:
Given : Sample size : n= 33
Critical value for significance level of 
: 
Sample mean : 
Standard deviation : 
We assume that this is a normal distribution.
Margin of error : 
i.e. 
Hence, the margin of error is
Answer:
see explanation
Step-by-step explanation:
Under a rotation about the origin of 90°
a point (x, y ) → (- y, x ), thus
A(2, 2 ) → A'(- 2, 2 )
B(2, 4 ) → B'(- 4, 2 )
C(4, 6 ) → C'(- 6, 4 )
D(6, 4 ) → D'(- 4, 6 )
E(6, 2 ) → E'(- 2, 6 )
The graph is shown below.
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