The label on a 1 1/2 pound bag of flour states that it will make 225 cookies. how many cookies will 1 pound of flour make?

You can use ratios here. the first ratio is:
1.5 pounds = 225 cookies

the second ratio is:
1 pound = x cookies

so we can divide both sides by whatever is easier to multiply by
(1.5lbs) / (225)cookies = 1

(1lbs) / (x cookies) = 1

since they are both equal to 1 we can set them equal to eachother

1.5lbs / 225 cookies = 1lbs \ x cookies

cross multiply

1.5lbs * x = 225(lbs *cookies)

x = 150 cookies

so the answer is 150 cookies

there is actually a short cut for this too. i see that the 1.5 lbs and the 1 lbs have a common factor of .5 lbs

i then see that 1.5lbs is 3 * .5lbs and 1lbs is 2 * .5lbs

so if we look at the 3 times .5 goes into 1.5 we can divide 1.5lbs by 3 to get the 0.5lbs

225/3 = 75

now we see there are two 0.5lbs in 1lbs needed for final answer
.5lbs = 75 cookies

so we can multiply the 0.5lbs value by 2 and get the answer which is the same as above. 150 cookies

75 cookies * 2 = 150 cookies