In

7
days, a group of workers can plant
21
acres.
What is their rate in acres per day?

21acres/7days = 21/7 = 3 acres/day

In 9 days, a group of workers can plant acres 63

What is their rate in acres per day?

Trey 48 reads chapters of a book in 6

hours.
What is his rate in chapters per hour?

Lena types at a rate of 10 words per minute.

How many words does she type in 5 minutes?

To find the rate in acres per day, we need to divide the total number of acres (21 acres) by the number of days (7 days).

Rate (acres per day) = Total acres / Number of days

Rate (acres per day) = 21 acres / 7 days

Now, let's do the calculation:

Rate (acres per day) = 3 acres per day

So, the rate at which the group of workers can plant is 3 acres per day.