Question

Each of the 15 rows in a stack of bricks contains 3 fewer bricks than the row below. The bottom row has 43 bricks. How many bricks are in the stack?

Answer 1

It's an arithmetic series,
43+40+37+...
Remember formula for this?

Answer 2

Yeah, sn=d(a1+an)/2

Answer 3

How can you sold it if you don't know the "Nth" therm, or how many total bricks there are?

Answer 4

solve*

Answer 5

Then find an first.

Answer 6

\[a_n=a_1+d(n-1)\]

Answer 7

What is the first term?

Answer 8

43

Answer 9

Oh, really? and the common difference is -3?

Answer 10

Yep,

Answer 11

I was thinking of it like a 'Cigular, raising the bars" situation where it started out as a small number and sequentially got larger

Answer 12

Thanks for the help man, saved my day

Answer 13

No problem :)