This week, Sarah spent a total of 120 minutes studying. This total was 20 more minutes than 4 times the amount of minutes she studied last week. How many
minutes did Sarah spend studying last week?

She spent 25 minutes studying last week

Step-by-step explanation:

L = last week

120 = 4L + 20

Subtract 20 from either side

100 = 4L

Divde either side by 4

25 = L

step-by-step explanation:

whole numbers.

step-by-step explanation:

we are given the average monthly rainfall (in millimeters) model r(m) for the years 1900-2009 as a function of the month number m.

as we can see m is taken for the number of months for years 1900-2009.

we know that number of months can't be a negative number or decimal number or a fraction.

so, the number of months could be only positive whole numbers.

therefore, whole numbers is more appropriate for the domain of r.