2 years is the same as 24 months, so the equation would be:
685 = 24x + 85, where x is the monthly fee.
600 = 24x
600/24 = x
x = 25
The monthly fee is $25.
Since she has seven key the probability that the first one will open the door is

if it takes three attempts to open the door,the probability is

if the three attempts would not work
then the probability that the fourth attempt will open the door is

hope this helps
Answer:
132−15+12
Step-by-step explanation:
The value of 2 in 2481 is 1000 less times the value of 2 in 5072