Answer:
15 gallons
Step-by-step explanation:
Given that:
Pumping rate is modeled by the equation :
Q(t)=45-t gallons per minute ; where t is in minutes
Number of gallons in tank after 30 minutes ;
Q(t)=45-t
Q(30) = 45 - 30
Q(30) = 15
Hence, Number of gallons in tank after 30 minutes is 15 gallons
Answer:

Step-by-step explanation:
The given exponential form is:

The base of the given expression on the right is 13 and the exponent is 2.
The number is 169.
In terms of logarithms, the base still remains the base and the exponent becomes the result of the logarithm of the number 169 to the given base 13.

First, sum up the total expenses for the original plan
Duque de Caxias + Campinas + Rio de Janeiro + Guarulhos = 242+185+193+120 = R$740
It is clearly over the intended budget. The average cost per itinerary is around R$200 so we will consider making a swap on either Duque de Caxias and Rio de Janeiro. Possible answers are (b) or (c)
for (b) Replace Duque de Caxias with Fortaleza, we will have
Fortaleza + Campinas + Rio de Janeiro + Guarulhos =
⇒ 201+185+193+120 = R$699 ⇒ This is exactly the budget intended for the trip
for (C) Replace Rio de Janeiro with Porto Alegre
Duque de Caxias + Campinas + Porto Alegre + Guarulhos =
⇒ 242 + 185 + 153 +120 = R$ 700 ⇒ This is over R$1
The answer is (b)