A man bought 42 stamps, some 13¢ and some 18¢. How many of each kind did he buy if the cost was $6.66? If x represents the number of 13 cent stamps and y the 18 cent stamps, which system represents the problem? x + y = 42 and 0.13x + 0.18y = 6.66 x + y = 6.66 and 0.13x = 0.18y 0.13x + 0.18y = 42 and x + y = 6.66

24 $.18 stamps  (y)= $4.32
18 $.13 stamps (x)= $2.34
                            ______
                             $6.66    
x + y = 42                          18 + 24 = 42  (stamps)
.0.13x + .0.18y= 6.66        $ 0.13 (18) +$ 0.18 (24) = $6.66