I think it is A. -7
I think that because FG's distance is 6, and if FG and HI are equal, then their distances should both be equal to 6.
For lines to be parallel, the slopes have to be the SAME.
For lines to be perpendicular, the slopes have to be the exact opposite. (opposite sign and number)
For example(perpendicular):
slope is 2
the perpendicular slope is -1/2
slope is -4/5
the perpendicular slope is 5/4
12. line a and b are perpendicular
13. Line a: y = 3/5x + 1
Line b: y = 3/5x - 2/5
Line c: y = 4/6 + 5/3x
line a and b are parallel
14. Line a: y = 3x + 6
Line b: y = 6 - 3x
Line c: y = 2/3x + 6
Neither, none of them are parallel or perpendicular
15. Line a: y = -2/3 + 4/3x
Line b: y = -1/4 - 3/4x
Line c: y = 5 + 3/4x
line a and b are perpendicular
Solution
The table below is the required sample space of the to fair die
From the above table
The sample space contain 36 outcomes
Event A: The sum is greater than 9
we will look at the table and count all the elements that are greater than 9
There are 6 elements (they are 10, 10, 10, 11, 11, 12 from the table)
The probability for event A will be

P(A) = 1/6
Event B: The sum is an even number.
We will look at the table and count the number of elements that are even
There are 18 elements (notice that there are 3 even number on each of the 6 rows of the table)
The probability for event B will be

p(B) = 1/2
I think this is the answer
A)Cathy had $6 at first
B)Selena has $24 at first
Answer:
By making ‘a’ the subject, I believe you mean isolate the variable ‘a’.
1/a - 1/b = 1/c : add 1/b to both sides
1/a = 1/b + 1/c : combine the unlike fractions by finding a common denominator, bc is the common denominator
1/a = (1/b)(c/c) + (1/c)(b/b) : simplify
1/a = (c/bc) + (b/bc) : add numerators only, because the denominators match
1/a = (c + b)/bc : multiply both sides by a
1 = (a)[(c + b)/bc] : multiply both sides by the reciprocal of [(c + b)/bc] which is [bc/(b + c)]
1[bc/(b + c)] = a
a = bc/(b + c)
This will not work if c = -b, because then you would be dividing by zero.
Example: 1/2 - 1/3 = 1/6 a = 2, b = 3 c= 6
a = bc/(b + c) => 2 = (3 x 6)/(3 + 6) => 2 = 18/9 => 2 = 2.
Step-by-step explanation: