Extension: suppose that there is some positive number bb so that
logb(5) = 0.84.

b = 6.79

Step-by-step explanation:

Data provided:

logb(5) = 0.84

Now,

From the properties of log function

logₓ (z)=  (where the base of the log is equal for both numerator and the denominator)

also,

log(xⁿ) = n × log(x)

thus,

using the above properties, we can deduce the results as:

logₓ(y) = n is equivalent to y = xⁿ

Thus,

logb(5) = 0.84

⇒ = 0.84

or

log(5) = 0.84 × log(b)

or

log(5) =                (as log(xⁿ) = n × log(x) )

taking the anti-log both sides

we get

5 =

or

b = 6.79

answer:

payment just for service  

→

$

87.12

payment for service including tax

→

$

94.09

explanation:

service only with 20% tip  

→

$

72.6

(

1

+

20

100

)

=

$

87.12

in the opening of the question the word 'service' is associated only with the pretax value.

the closing part of the question asks: how much did she pay for the  

service

−−−−−−  

so technically the answer is  

→

$

72.6

(

1

+

20

100

)

=

$

87.12

however, the intention of the question provider may have been that your answer is to be  

$

87.12

(

1

+

8

100

)

=

$

94.09

to 2 decimal places.

'

payment just for service  

→

$

87.12

payment for service including tax

→

$

94.09

tony b

mar 21, 2017

answer:

trying to explain it another way

explanation:

service charge  

.

→

$

72.60

20% tip  

20

100

×

$

72.60

=

$

14.52

−−−−−−  

←

add

$

87.12

tax  

8

100

×

$

87.12

=

$

6.97

−−−−−  

←

add

$

94.09

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