The air pressure inside Jason's bike tires decreases by about 6% each week. The original pressure was 45 pounds per square inch (psi). What is the tire pressure after 6 weeks?

Lets do this week by week

beginning pressure 45 pounds

end of week 1

45 *.06 = 2.7

45 - 2.7 = 42.3

end of week 2

42.3 *.06 = 2.538

42.3 - 2.538 = 39.762

end of week 3

39.762 *.06 = 2.38

39.762 - 2.38 = 37.37

end of week 4

37.37 *.06 = 2.2425

37.37628 - 2.2425 = 35.12

end of week 5

35.12 *.06 = 2.107

35.12 - 2.107 = 33.012

end of week 6

33.012 *.06 = 1.98

33.012 - 1.98 = 31.03

Here is the fast way to get to this answer.

do 1-.06 =.94

then do

45 (.94) (.94) (.94) (.94) (.94) (.94) = 31.04