How many ways are there to choose three donuts from 4 varieties if there must be an odd number of glazed donuts? the number of glazed must be 1 or 3?

1 glazed and 2 others     or     3 glazed and 0 others

           1 x 3 x 3               +                 1 x 1 x 1

                9                     +                       1

                                       10

10

8(-10x+3.5y-7)

8×-10x + 8×3.5y + 8×-7

-80x + 28y - 56

therefore

-80x+28y-56 is the correct answer

$25

step-by-step explanation:

25 - 4.50 = 20.5

20.5 / 2 = 10.25

10.25 + 10 = 20.25

20.25 - 12.50 = 7.75

therefore the answer is $25 as shown as the first number.