Nancy started the year with $435 in the bank and is saving $25 a week. Shane started with $875 and is spending $15 a week. When will they both have the same amount of money in the bank?

Set up the Account equation A(w) where w is the number of weeks that pass.

Nancy (we add since savings means she accumulates more):
A(w) = 25w + 435

Shane (we subtract since spending means he loses more):
A(w) = 875 - 15w

Set both A(w) equations equal to each other to since we want to see what w is when the account are equal:
25w + 435 = 875 - 15w