Author: Chicago Public Schools
Last saved by: mike

Name________________________

                                         SYSTEM OF EQUATIONS-SUBSTITUTION #3—KEY

Directions:  Solve each system of equations below by the substitution method. Substitute the value of a variable                        
                     from one equation into the other equation, then solve that equation for x or y.

1)      3x + 2y = 35               			 2)     4x + 7y = 31			        3)     2x + 8y = 42

          y = x + 5                     		          y = x - 5 			                 x = y + 6

      3x + 2(x + 5) = 21
     3x + 2x + 10 = 21

        x =    5           y =   10    		           x =    6           y =    1    	                x =    9           y =     3    

4)      5x + 2y = 65			             5)     10x + 3y = 62			        6)      4x + 8y = 48

          y = x - 6 		                                   y = x – 1 			                  x = 2y + 4 

        x =   11           y =    5    		            x =    5           y =    4    	                x =     8           y =     2    

7)     20x + y = 146			             8)      x + 2y = 5			        9)     6x + 3y = 69

          y =  x - 1 		                                   x = 4y + 2			                  y = 4x - 7

        x =    7           y =    6    		            x =    4           y =  0.5    	                x =    5           y =     13    

www.imathworksheets.com