Jina spends $20 dollars each time she travels toll roads. She started the month with $250 in her account, and so the amount of money she has left in her account after 1 trips is A(1) = 250 - 20t
a. How much money does she have left in her account after 4 trips? Show all work.
b. What is the largest number of trips she can take without running out of money in her account?

a) $170

b) 12

Step-by-step explanation:

A = 250 - 20t

where A is Jina's account balance and t is the number of trips she takes.

a)  If Jina takes 4 trips, then t = 4.  

Substitute t = 4 into the given equation:

A = 250 - (20 x 4)

  = 250 - 80

  = 170

So Jina has $170 left in her account after 4 trips.

b) The calculate the maximum number of trips Jina can take without running out of money, set A to zero and solve for t:

when A=0:                           0 = 250 - 20t

Add 20t to both sides:    20t = 250

Divide both sides by 20:     t = 12.5

Therefore, Jina can take 12.5 trips.  However, she can't take a half-trip so we should round the number down to 12 trips (as after 12 trips she will only have enough money left for half a trip).

So, the largest number of trips Jina can take without running out of money is 12.

a

step-by-step explanation:

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