1

[tex]\large\sf{}5 \times 4 - 3 \times 4 \\ \large\sf{}20 - 12 \\ {\large\boxed{\boxed{  { \large \sf 8}}}}[/tex]

2

[tex]\large\sf{}8 \times 6 - 45 \\ \large\sf{}48 - 45 \\ {\large\boxed{\boxed{  { \large \sf 3}}}}[/tex]

3

[tex]\large\sf{}10 + 5 \times 8 - 1 \\\large\sf{} 10 + 40 - 1 \\ \large\sf{}50 - 1 \\ {\large\boxed{\boxed{  { \large \sf 49}}}}[/tex]

[tex]{\large\boxed{\boxed{  { \large \sf Bons~Estudos }}}}[/tex]

Resposta:

a)8

b)3

c)49

Explicação passo-a-passo:

a)5x4=20

3x4=12 20-12=8

b)8x6=48 48-45=3

c)5x8=40 10+40=50-1=49

cabou