Mathematics - Addition and Subtraction - Subtraction within 20 - Subtraction Facts 11-20

Problems where minuend is 11-20, subtrahend is 1-10, result is 1-10. Examples: 14-8=?, 17-9=?, 12-5=?. 20 problems. Include a 'hint' button that shows: (a) number line with jumps, or (b) related addition fact. Track speed and accuracy. Show fact family connection: if 14-8=6, then 6+8=14.