Please answer the following question by reasoning step-by-step.
Thomas has been saving $40 in the bank every month for six years. His friend Joseph has been saving 2/5 times less money per month. How much money are they having in their savings account altogether?

4608
Thomas has been saving for six years, and since each year has 12 months, he has been making savings for 6 * 12 = 72 months.

Since Thomas has been saving $40 in the bank every month for six years, he has saved 72 * $40 = $2880.

Joseph has been saving 2 / 5 times less money per month than Thomas, meaning he has been saving 2 / 5 * $40 = $16 less per month.

The total amount of money that Joseph has been saving per month is $40 - $16 = $24.

In six years, Joseph has saved $24 * 72 = $1728.

Together, they have saved a total of $2880 + $1728 = $4608.

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Thus, the answer is 4608