<image>Many discoveries in ancient Chinese mathematics were among the world's forefront, with the "Yanghui Triangle" (as shown in the figure) being one example.

The construction rule for this triangle is as follows: the numbers on both sides are 1, and every other number is the sum of the two numbers directly above it. In fact, this triangle provides the coefficients of the expansion of (a+b)^n (where n is a positive integer) arranged in descending powers of a. For example, the three numbers 1, 2, 1 in the third row of the triangle correspond exactly to the coefficients in the expansion of (a+b)^2 = a^2 + 2ab + b^2; the four numbers 1, 3, 3, 1 in the fourth row correspond exactly to the coefficients in the expansion of (a+b)^3 = a^3 + 3a^2b + 3ab^2 + b^3, and so on. According to the above rule, the largest coefficient in the expansion of (a+b)^4 is ____; the value of the expression 7^5 + 5×7^4×(-5) + 10×7^3×(-5)^2 + 10×7^2×(-5)^3 + 5×7×(-5)^4 + (-5)^5 is ____.