Last year, frannie sold 48 stickers. this year, frannie sold 60 stickers.
by what percent did the number of stickers frannie sold change?

a. 80% decrease
b. 12% increase
c. 20% decrease
d. 25% increase

hello from mrbilldoesmath!

answer:

a(n) - a(n-1) -3

discussion:

this ones a bit interesting. given a(n) = 5 - 3n consider this:

a(n-1) = 5 - 3(n-1)

          = (5 - 3n) + 3             => but a(n) = 5 - 3n, the first term

          = a(n)   + 3                 => subtract 3 from both sides

a(n-1) -3 = a(n)  

or

a(n) - a(n-1) -3

you,

mrb

40 i don’t know lololol