a) Ta có phương trình: x - 93 = 175/25
Simplifying the right side of the equation, we get: x - 93 = 7
Adding 93 to both sides of the equation, we get: x = 7 + 93
Simplifying the right side of the equation, we get: x = 100

Vậy số tự nhiên x là 100.

b) Ta có phương trình: 4(20017 - 16x) = 100 - 32
Simplifying the left side of the equation, we get: 80068 - 64x = 68
Subtracting 80068 from both sides of the equation, we get: -64x = -79900
Dividing both sides of the equation by -64, we get: x = -79900/-64
Simplifying the right side of the equation, we get: x = 1248.4375

Vậy số tự nhiên x không tồn tại.

c) Ta có phương trình: 5 * 2^(2x) = 80
Dividing both sides of the equation by 5, we get: 2^(2x) = 16
Taking the square root of both sides of the equation, we get: 2^x = 4
Taking the logarithm base 2 of both sides of the equation, we get: x = log2(4)
Simplifying the right side of the equation, we get: x = 2

Vậy số tự nhiên x là 2.