Part B is saying to equal the both equations, so
5x + 2 = 5x + 5
Take a look, we have the same multiplicative to our variable, but we have different sums, so, if we just say x = 0 we wil have:
5.0 + 2 = 5.0 + 5
0 + 2 = 0 + 5
2 = 5
And of course it's not true, 2 will never be equal to 5, so we can say there's no solution for x.
Another way to see this is:
5x + 2 = 5x + 5
5x - 5x = 5 - 2
0 = 3
0 of couse isn't equal to 3.
