There are 4 trucks for every 5 cars in a parking lot. How many trucks and cars could be in the parking lot?
2 answers:
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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
x = 3 or x = 1
note that log 5 is usually taken to mean 5
using the law of logarithms
logx - logy = log ()
the right hand side can be expressed as
log 10000 - log 16 = log () = log 625
divide both sides by log 5
x² - 4x + 7 = = 4
subtract 4 from both sides
x² - 4x + 3 = 0 ← in standard form
(x - 3 )(x - 1) = 0
equate each factor to zero and solve for x
x - 3 = 0 ⇒ x = 3
x - 1 = 0 ⇒ x = 1