Explicação passo a passo:

2/5 * 1/3 * ( 10 * 30)

2/5 * 1/3 * 300 m²

2/5 * 1/3 = ( 2 * 1 )/( 5 * 3 ) = 2/15

2/15 * 300 m² = ( 2 * 300 )/15 = 600/15 = 40 m²>>>>resposta