We define the following variables:
R = # of rectamgular tables
C = # of circular tables
From the statement we know that we have a total of 18 tables, so the # of rect. tables plus the # of circ. tables must sum 18:
We also know that we have 130 occupied seats, so we can write the following equation in terms of R and C (taking in account that each one can have 8 and 6 persons, respectively):
So we must solve the following system of equations:
In order to solve the system we can do the following steps: