The factorial ! just means we multiply by every natural number less that the value so
6! =6×5×4×3×2×1= 720
for permutations we use the formula n!/(n-r)!
so we have 8!/(8-5)!=8!/3!=8×7×6×5×4
for combinations s we have n!/(n-r)!r!
so we have 12!/(12-4)!4!=12!/8!4!=12×11×10×9/4×3×2=11×10×9/2=99×5
$96(2 payments) = $192
$192/(12 months) = $16 per month (she should set aside)
He bought last year and year later total is $104.3
Each share he sold 62.80 with tax is 0.03
62.80x1.03= $64.684 for each share
So there are 40 shares
64.684 x 40= $2587.36
Last one should be less than 3/4