Question

Y=5x-25 , the output is -25 what’s the input

Answer 1

y = 5x - 25

output = -25

-25 = 5x - 25

5x = -25 + 25

5x = 0

x = 0

Answer: Input = 0

Answer 2

in the equation y = 5x - 25, x is the input and y is the output. You know this because you start with some x value, apply some operations, and you get the answer y. So if -25 is the output, then y=-25. To find the input, just solve for x:
y=5x-25
-25=5x-25
0=5x
x=0
So the input is 0.