Idon't understand and how do i do it

Ok so she has 3 small containers holding 8 pounds of birds seeds and 6 large containers of bird seed that each hold 12 pounds of bird seed, and she has already used 4 pounds so lets find how many pounds of bird seed she has altogether 8*3=24 6*12=72 and adding the leftover 24+72-4=92 now she wants to fill 30 bird feeders needing 2 pounds each, would require 60 pounds of bird seed now that she used 60 more pounds of seed 92-60=32 she would have 32 pounds of bird seed leftover now an equation to use to solve this is (3(8))+(6(12))-4-(30(2))=the amount of bird seed left over hopefully this gave you an idea on how to do this the way you are supposed to 

x = 11

Step-by-step explanation:

Complementary means they add up to 90°

So add the angles up and set them equal to 90°

3x - 4 + 5x + 6 = 90

ADD the x's

8x - 4 + 6 = 90

COMBINE the -4 and 6

8x +2 = 90

SUBTRACT 2 from both sides.

8x = 88

DIVIDE by 8 on both sides.

8x/8 = 88/8

x = 11