1. 54 + 9 = (50 + 4) + 9 = 50 + (4 + 9) = 50 + 13 = 50 + (10 + 3) = (50 + 10) + 3 = 60 + 3 = 63;2. 7 + 37 = 7 + (30 + 7) = 30 + (7 + 7) = 30 + 14 = 30 + (10 + 4) = (30 + 10) + 4 = 40 + 4 = 44;3. 27 + 5 = (20 + 7) + 5 = 20 + (7 + 5) = 20 + 12 = 20 + (10 + 2) = (20 + 10) + 2 = 30 + 2 = 32;4. 4 + 28 = 4 + (20 + 8) = 20 + (4 + 8) = 20 + 12 = 20 + (10 + 2) = (20 + 10) + 2 = 30 + 2 = 32;5. 85 + 6 = (80 + 5) + 6 = 80 + (5 + 6) = 80 + 11 = 80 + (10 + 1) = (80 +10) + 1 = 90 + 1 = 91;6. 9 + 43 = 9 + (40 + 3) = 40 + (9 + 3) = 40 + 12 = 40 + (10 + 2) = (40 + 10) + 2 = 50 + 2 = 52;7. 36 + 9 = (30 + 6) + 9 = 30 + (6 + 9) = 30 + 15 = 30 + (10 + 5) = (30 + 10) + 5 = 40 + 5 = 45;8. 3 + 58 = 3 + (50 + 8) = 50 + (8 + 3) = 50 + 11 = (50 + 10) + 1 = 60 + 1 = 61;9. 75 + 5 = (70 + 5) + 5 = 70 + (5 + 5) = 70 + 10 = 80;10. 5 + 55 = 5 + (50 +5) = 50 + (5 + 5) = 50 + 10 = 60.