9 Mystery Pictures with 27 Color by Code (Color By Number) Math Worksheets. Each worksheet includes 10 unique problems. All pictures have a colored answer key. Solve the math problem, look at the color next to it, and then color in ALL of the squares that have that answer. Examples: n = 4; 9n + 15 = ? b = 15; 10 + b + 13 = ? b = 5; 4b - 6 = ? z = 4; 8 ÷ z = ? a = 8; 6a = ? Please CLICK HERE to view other Math Mystery Picture products