The answer would be D, because m<4 would be supplementary with the angle that's 43 degrees. Supplementary angles add up to 180, so this could be found through the following equation.
The rest of the angles are not correct because if you add 142+56 (adjacent angles) or the unknown angles (angle 1 + angle 2), it doesn't equal 180. You can picture it as angle 3 and its adjacent angle (56°) equal to 180 sience there sharing one straight line thus being 180°
To add integers with different signs, subtract the lesser absolute value from the greater absolute value. Use the sign of the integer with the greater absolute value for the sum. The following steps will be useful to find the sum of two numbers with different signs.
