Consider factors of 42, then if the factors can be added or subtracted.
42 = 42 * 1
42 = 21 * 2
42 = 14 * 3
42 = 7 * 6
Since none of these can be added or subtracted to equal 15, no intergers satisfy these criteria.
First u subtract 19-4= 15 and then b= 15. So then 4+15=19. B=15
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$15 because a mean would allow him to spend $250 over the five months BUT he has already spent $235.
$250 - $235 = $15