Answer:
6
Step-by-step explanation:
[ 1 ] Given
[ 2 ] Exterior Sides Opposite Rays
[ 3 ] Definition of Supplementary angles
[ 4 ] First substitution
[ 5 ] Subtraction Property of Equality
[ 6 ] Second Substitution
[ 7 ] If corrsp. equal, the lines ||
You do 20 teachers multiplied by 7 departments because there are 20 teachers 7 times.
Multiplying them gets you 140.
140 teachers are there in total.