They're also available for nearly all grade levels. There are printable middle school, high school, elementary school, and even pre-school worksheets.
Review subtraction of 2 numbers whose sums would be 18 or less
I recommend getting one of these books when you first begin homeschooling and use it as a reference throughout your homeschool journey. Regardless of how long you homeschool, you'll always have doubts and questions about how your child is performing.A scope and sequence book can put your mind at ease.
Worksheets also, when used properly, provide both the students and parent / tutor immediate feedback as to the child's progress. This means they can be used to point out areas where the student needs further reinforcement.