What’s the answer to this? Thanks!

D

Step-by-step explanation:

I used a triangle calculator I'm not really sure how to calculate it by hand. if the angle of sides 4 and 15 is set to 1 then the min is 11.33 and if the andle of sides 4 and 15 are set to 179 then the max is 18.99952

Sorry if this isnt enough, but i am sure.

D.  11 < x < 19.

Step-by-step explanation:

The third side x is between 11 and 19 cm.

Consider sides AB (length 4) and BC (length 15) of the triangle.

Consider the angle between AB and BC is slightly less than 180 degrees.  To get from point A to point C, we have to travel almost the entire length of A to C, which is from A to B and then B to C, so a bit less than 19 cm.

Consider the angle between AB and BC is slightly more than 0 degrees.  To get from point A to point C, we subtract the length of AB (because we're already further along BC), so 15 - 4, a bit greater than 11.

8(-10x+3.5y-7)

8×-10x + 8×3.5y + 8×-7

-80x + 28y - 56

therefore

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