Since each table had 7 women and 3 men at each table, that would mean each table has 10 people. Since there are 9 tables he was waiting on, and 10 people at each table, multiply 9 x 10, and you will find that he served 90 people in total.
The two triangles are congruent through SSS which means Side-Side-Side. This is because each side of the triangle correlates between the two of them. They both have a 8, 6, and 3 side.
