So, first you need to replace the variables ( x and y) for numbers. In this case, the numbers are 7 for x and 14 for y. Now that you replaced the numbers for the variables, the equation looks like this: -5x7+3x14=7. To make sure the equation is correct, you need to multiply -5x7 (which is -35), then you need to multiply 3x14 (which is 42). Now, you need to add -35+42, which gives us 7. So, the equation is correct.
You are given the equation and points (x, y) to plug into that equation. See which ones satisfy. The left side must equal the right side (7 in this case) when evaluating...
-5(7) + 3(14) = 7
-35 + 42 = 7
7 = 7
The point (7, 14) works. The other points will not yield the same result..
to be able to reproduce sexually you need enough of the same species to mate with. A says no individuals to reproduce with but for that it would be better if they were asexual. D says they change living environment and that usually changes the amount of same species animals that are around to reproduce with.
