To express 127 as a sum of 100, another number, and 7, we first find the number that, when added to 100 and 7, equals 127.
We can set up the equation: \[ 127 = 100 + x + 7 \] where \( x \) is the number we need to find.
Now, combine 100 and 7: \[ 100 + 7 = 107 \]
Thus, we rewrite the equation: \[ 127 = 107 + x \]
To find \( x \), we can rearrange this: \[ x = 127 - 107 \] \[ x = 20 \]
So, the expression is: \[ 127 = 100 + 20 + 7 \]
In conclusion, the complete equation is: \[ 127 = 100 + 20 + 7 \]
Therefore, the answer to the blank is 20.