At Macon County High School, a classroom is 400 ft2. After the teacher sets up her desk, computer, and podium, there are 250 ft2 left for student desks. If each desk takes up 8 ft2 of room, how many desks can fit in the classroom?
A) about 19
B) about 25
C) about 31
D) about 50

C-31

Step-by-step explanation:

You would divide 250 by 8. Which equals 31.25. So the answer would be about 31.

cross multiplying, we get :

⇒ (3) × (5) = (9) × (x)

⇒ 15 = 9x

delaney would like to make a 5lb nut mixture that is 60% peanuts and 40% almonds.

she has several pounds of peanuts and several pounds of a mixture that is 20% peanuts and 80% almonds.

let 'p' represent the number of pounds of peanuts needed to make the new mixture, and  

let 'm' represent the number of pounds of the 80% almond-20% peanut mixture.

:

p + m = 5

therefore

m = (5-p)

write an equation based on the percent of peanuts

1p + .2m = .6(5)

replace m with (5-p)

p + .2(5-p) = .6(5)

p + 1 - .2p = 3

p - .2p = 3 - 1

.8p = 2

p = 2/.8

p = 2.5 lbs of peanuts required

then

5 - 2.5 = 2.5 lbs of the peanut/almond mixture required

:

a) what is the system that models this situation?

p + m = 5

1p + .2m = .6(5)