The slope of BC is 
Step-by-step explanation:
Let us revise some notes about slopes of lines
- If two lines are parallel, then their slopes are equal
- If to lines are perpendicular, then the product of their slopes is -1, that means if the slope of one is m, then the slope of the other is

∵ ABCD is a rectangle
∵ AB // CD
∴ The slope of AB = the slope of CD
∵ BC ⊥ AB
∴ The slope of BC × the slope of AB = -1
∵ The slope of AB = 
- To find the slope of BC reciprocal the slope of AB and reverse its sign
∴ The slope of BC = 
The slope of BC is 
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You can get 9 because in one foot there is 12 inches and there in 9 feet
Answer:
$35
Step-by-step explanation:
7 customers - 2 who didn't tip = 5 who did tip
$7 from those who did tip * 5 ppl who tipped = $35 earned
X + 12 = 20
x + 12 -12 = 20 -12
x = 8
Answer:
is sometimes positive and sometimes negative.
Step-by-step explanation:

Take 

Take 

Hence
for
and
for 
So
is sometimes positive and sometimes negative in the interval.