Question

How do you find the missing number so that the equation has no solutions `5x-11=?x+19`?

Answer 1

Let's first bring the `x`'s to one side and the numbers to the other

Explanation:

Subtract `?x` and add `11` on both sides:
`5x-?x=19+11->(5-?)x=30`

If `?=5` then `5-?=0` and the equation would be:
`(5-5)x=30->0x=30->0=30`

And this is obviously not true.