Find the gcf and lcm for 4,8,12 with work

Gretchen is setting up for a banquet. she has 300 chairs and needs to distribute them evenly among t tables. how many chairs should she put at each table? write your answer as an expression.

If 1/√5+1/√5+1=p+q√r , find the values of p, q and r

Find the solution of this system of equation -7x+y=-20 9x-3y=36