1) Simplifying the expression a+4b-a-7b, we get:

a + 4b - a - 7b = (a - a) + (4b - 7b)
= 0 - 3b
= -3b

Therefore, the simplified expression is -3b.

2) Simplifying the expression -2x+3,7+2x-5, we get:

-2x + 3 + 7 + 2x - 5
= (-2x + 2x) + (3 + 7 - 5)
= 0 + 5
= 5

Therefore, the simplified expression is 5.