My first thought when I read this problem was "11 is a factor of 1155." Indeed, 1155 equals 11 times 105. Next, determine factors of 105. I see that 5 is a divisor of both 10 and 5, so that 105 equals 5 times 21.
Adding together these three integers: 11+5+21 = 37
But wait! 21 can be factored (e. g., into 7 times 3).
You'll need to identify all of the several sets of 3 positive integers each and find the sum of each set. Only after you've done this can you choose the set whose sum of the three integers is the smallest. Please show your work, so that others can give you feedback on it.
The equation is valid for positive values of x not greater than 40.
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Personally, I might put the domain at 1 ≤ x ≤ 40, because there's no point in using the equation (or parking the bus) if zero people are going on the trip.
