In this case, all letters are unique.
Start by holding the first letter:
E - XAM
E - XMA
E - MAX
E - MXA
E - AXM
E - AMX
So there are 6 combinations here.
Repeat for all 4 letters.
6 x 4 = 24
This is same as 4x3x2x1.
For 3 unique characters, it is 3x2x1.
For 5 unique characters, it is 5x4x3x2x1
And so on...
Decimals are not an integer, so that’s making 0.54 not an integer
Rosa has saved $490 in 6 weeks.
To find the answer to this, simply plug the number of weeks in for the value of x and solve.
f(x) = 250 + 40x
f(6) = 250 + 40(6)
f(6) = 250 + 240
f(6) = 490
Subtract 363,321 from 778,871. Which gives you 415,550 more geese than crows :)