Cailyn got 2 out of the 3 questions correct on her test. What is her grade?
1 answer:
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Answer:
The monthly cost for 45 minutes is $18.42
Step-by-step explanation:
Let
x -----> the total calling time in minutes
y ----> the monthly cost in dollars
we have the ordered pairs
(42,18.15) and (90,22.47)
step 1
Find the slope
The formula to calculate the slope between two points is equal to
substitute the values
step 2
Find the linear equation in point slope form
we have
substitute
step 3
Find the monthly cost for 45 minutes of calls
For x=45 min
substitute the value of x in the linear equation and solve for y
therefore
The monthly cost for 45 minutes is $18.42