Respuesta :

3 x 78

= 3 x (70+8)

= 210 + 24

= 234
[tex]3\times78\\-----------------\\78=70+8\\-------------------\\=3\times(70+8)\\------------------------\\use\ distributive\ property:a(b+c)=ab+ac\\--------------------------\\=3\times(70)+3\times(8)=210+24=\huge\boxed{234}[/tex]