Directions: Using the integers -9 to 9 (excluding 0) at most one time each, fill in the blanks to create two distinct perpendicular lines.
1 x + 2 y = 4
-6 x + 3 y = 5
2 x + 3 y = 9
-6 x + 4 y = 8
Any solution where the x and y coefficients swap and one is negative. Students will need to use multiples to avoid repeating values. The constant term can take any remaining value.
Source: Louise Pepper with answers from the students of Kings College Alicante, Spain