Explicação passo-a-passo:

[tex](3 \times 10 {}^{3} ) {}^{} \times (5 \times 10 {}^{3} - 15 \times 10 {}^{4} ) = [/tex]

[tex](3 \times 10 {}^{3} ) \times 5.10 {}^{3} (1 - 3.10) = [/tex]

[tex](3 \times 10 {}^{3} ) \times 5.10 {}^{3} (1 - 30) = [/tex]

[tex](3 \times 10 {}^{3} ) \times .10 {}^{3} .( - 29) = [/tex]

[tex]10 {}^{3} \times 3. - 29 = [/tex]

[tex]10 {}^{3} \times - 87 = 1000 \times - 87 = - 87000[/tex]