Respuesta:
a) 12 + 6 = 18 × 5 = 90 ÷ 2 = 45
b) 13.2 + 7.3 = 20.5 × 6.8 = 139.4 ÷ 2 = 69.7
c) 20 + 10 = 30 × 9 = 270 ÷ 2 = 135
d) 22 + 12 = 34 × 10 = 340 ÷ 2 = 170
e) 30 + 15 = 45 × 14 = 630 ÷ 2 = 315
