The product of the two is 0, so one of them have to equal 0 as any number multiplied by 0 is 0.
First solution: x - 4 = 0
If x - 4 = 0, then x = 4. So the first solution for x is 4.
Second Solution: -5x + 1 = 0
Solving...
-5x + 1 = 0
-5x = -1
x = -1/-5
x = 1/5 or 0.2
So x = 0.2 and 4
