Question is a little uncertain with the number in parentheses but if Jill spent 3/4 hour and Jack 3/4 of her time then multiply together 3/4 x 3/4=9/16 of an hour. If your saying that Jill spent 9 and 3/4 hours and jack spends 1 3/4 as much time you still multiply but change to improper fraction first. Jill spent 9 x 4 + 3 hours which equals 39/4 hours and Jack spends 1 x 4 + 3= 7/4 as much time, now multiply 39/4 x 7/4=273/16, now reduce, 17 and 1/16