Solve the Equation: Finding the Missing Number in -25-?=100

We'll add ?+ to both sides to zero out the left side:

$-25-?+?=100+?$

$-?+?=0$

Therefore, we obtain:

$-25-0=100+\text{?}$

$-25=100+\text{?}$

We'll add minus 100 to both sides to zero out the right side:

$-25-100=100-100+\text{?}$

We should obtain the following:

$-125=0+\text{?}$

$-125=\text{?}$