How to graph these systems of equations

2-digit numbers less than 91 which are 1 less than a multiple of 10

Pete is making decorations for a dinner party. the instructions tell him to use 9 flowers for a medium-sized decoration. complete each statement to adjust the flowers for different-sized decorations based on these instructions.

What is the fewest number of full weeks briyana would have to work to have enough money? 8 weeks9 weeks 10 weeks11 weeks