Tracey is researching ways to increase the efficiency of a warehouse security service. While researching, she finds an electronic book that contains information relevant to her topic. Which three details should Tracey check to make sure the e-book is a credible and reliable research source?

substitute y = 2x - 4 to x + 2y = 12:

x + 2(2x - 4) = 12     use distributive property

x + (2)(2x) + () = 12

x + 4x - 8 = 12     add 8 to both sides

5x = 20     divide both sides by 5

x = 4

put the value of x to the first equation:

y = 2(4) - 4

y = 8 - 4

y = 4

i think the answer might compound

keep learning.

explanation:

i guess