Jack spends 1 1/2 times as long on his homework as Jill.

Last week, Jill spent 8 1/2 hours doing homework.

How long did Jack spend doing homework?

12 3/4 hours

Step-by-step explanation:

Jack spends 1 1/2 times as long on his homework as Jill.

Jill spends 8 1/2 in doing his home work.

Time spent by jack in doing his homework is jacks time multiplied by Jill's

That's

1 1/2 x 8 1/2

Change to improper fractions.

We have,

3/2 x 17/2

Multiply through

51/4 = 12 3/4

Jack spends 12 3/4 hours in doing his homework

12 3/4

Step-by-step explanation:

8.5 times 1 is 8.5

and 8.5 times. 5 is 4.25

so 8.5 plus 4.25 is 12.75 or 12 3/4