In october greg and thomas had the same amount of money in their savings account in november greg deposited $120 into his account thomas increased the money in his account by 20% when they compare their bounces they found out they were still equal

Assume the amount of money they both deposited in october is m.
in november, greg deposited 120$, so the total amount in his account became m+120
thomas increased his account by 20%, this meams that the amount of money in his account became: m+0.2m
since both values are still equal, we will equate the two equations and solve for m:
m+120 = m+0.2m
0.2m = 120
m = 600$