1/5 is your answer, sorry if it is wrong but I think it os right :)
-7/15.
You multiply the numerator and denominator to get -21/45. To simplify, divide each by the greatest common factor, which is three, to get -7/15.
1/6 since six people are eating the leftovers
Spaghetti sauce - $2.49
Spaghetti noodles - $1.58
Gallon of milk - $3.17
$2.49 + $1.58 = $4.07
$4.07 + $3.17 = $7.24
Answer - $7.24
Hope this Helps!!