25 percent is known to be 1/4 of a number, so if 50 teachers represent 1/4 of all the teachers, that means that in order to get a full number, we must multiple 50 by 4 in order to get all 100% of the teachers.
By doing 50x4, we can conclude that 200 teachers teach at the school (aka 100% of all teachers)
The two angles and the side included between them of one triangle are equal to the corresponding angles and the included side of the other triangle. (Angle, Common Side, Angle)