We are interested in selecting 2 people from the 7-person task force.
n = 7
r = 2
nPr = n! / (n-r)!
7!
------
(7-2)!
=
7!
----
5!
7×6×5×4×3×2×1
------------------------
5×4×3×2×1
= 7×6
= 42
Let w = number of weeks.
In week w,
Laura has: 720 + 30w
Taylor has: 1200 - 30w
Set the two amounts equal and solve for w, the number of weeks.
720 + 30w = 1200 - 30w
60w = 480
w = 8
They will have the same amount of money in 8 weeks.
Laura will have in 8 weeks:
720 + 30w = 720 + 30 * 8 = 720 + 240 = 960
Taylor will have in 8 weeks:
1200 - 30w = 1200 - 30 * 8 = 1200 - 240 = 960
They will both have $960 in 8 weeks.
You have to add all the numbers then leave one and subtract it
