Find minimum and maximum for these,objective

1.C = 10x + 7y,constraints:0<=x<=60,0<=y<=45,5x+6y<=420;

2.C=4x+6y,constraints:-x+y<=11,x+y<=27,2x+5y<=90;

3.C=4x+3y,constraints:x=>0,2x+3y=>6,3x-2y<=9,x+5y<=20

4.C=10x+3y,contraints:x=>0,Y=>0,-x+y=>0,2x+y=>4,2x+y<=13 using Linear programing(optimization)