Emma and rita are at a florist shop. they are planning to make bouquets of flowers for their grandmothers out of roses and carnations. the cost for a single rose is r, and the cost for a single carnation is c. emma will use 6 carnations and 4 roses for her bouquet, and rita will use 5 carnations and 6 roses. write expressions that represent the total cost of emma's bouquet, the total cost of rita's bouquet, and the total cost for both bouquets combined.