Tolong dijawab semua dan dikasih cara!

18. suhu = 5-7 = -2°C
19. suhu = -3 + 10 = 7°C
20. 2½:1½-1¼ = 5/2 x 2/3 - 5/4 = 5/3 - 5/4 = 5x(4-3)/(3x4) = 5/12
21. 16/5 = 15/5 + 1/5 = 3¹/5

18) 5°C - 7°C = -2°C (B)
19) -3°C + 10°C = 7°C (B)
20) 2 1/2 : 1 1/2 - 1 1/4 = 5/2 : 3/2 - 5/4
         = 5/2 x 2/3 - 5/4 = 5/12 (A)
21) 16/5 = 3 1/5

Semoga membantu ^_^