Jack spends 1 3/5 as long on his homework as Jill. Last week, Jill spent 7 1/4 hours doing homework. How long did Jack spend doing homework?

clearly,

(7 1/4)*(1 3/5) = 29/4 * 8/5 = ?

To find out how long Jack spent doing homework, we need to determine 1 3/5th of Jill's time.

First, let's convert Jill's time to a mixed fraction for easier calculation. Jill spent 7 1/4 hours on her homework, which is the same as 7 + 1/4 hours.

To add the whole numbers: 7 + 1 = 8.

So, Jill spent a total of 8 hours and 1/4 hour doing homework.

Next, we need to find 1 3/5th of Jill's time.

To calculate, we multiply Jill's time by 1 3/5.

8 1/4 hours × 1 3/5 = (8 × 5 + 1) / 4 × 3/5
= (40 + 1) / 4 × 3/5
= 41 / 4 × 3/5

To multiply fractions, multiply the numerators together and the denominators together:

= (41 × 3) / (4 × 5)
= 123 / 20

Therefore, Jack spent 123/20 hours doing homework.