In october, greg and thomas had the same amount of money in their savings accounts. in november, greg deposited $120 into his account. thomas increased the money in his account by 20%. when they compared their balances, they found that they were still equal. how much money did each person have in his account in october?

Let's give the variable that you are trying to answer for a symbol. Let's call it X.

X = the amount of money both Greg and Thomas had in October

We know that in November, Greg added $120 to his account. So, Greg's account has: X + 120

We know that Thomas increased the money in his account by 20%, so Thomas' account has: X + 0.2X, or 1.2X

We know that these two amounts are equal:
X + 120 = 1.2X

Solve for X:
X + 120 - X = 1.2X - X
120 = .2X
120 / .2 = .2X / .2
600 = X

Same length is comparing because it’s saying its the same and not different