First you need to know what 10% of 1100 is, so you take 1100 and multiply it by the decimal form of the percent which is .11 to get $121. Now we know that every month we will put $121 into the fund, now just divide the total amount you need in the fun, $700, by your $121 monthly input to get the number of months to save that amount. You should get around 5.79 months, so it'll be 6 months before he has 3 months of living expenses.
