Respuesta :

[tex]\boxed{4a}[/tex] ✅

[tex]\large\mathfrak{{\pmb{\underline{\red{Step-by-step\:explanation}}{\orange{:}}}}}[/tex]

[tex]a + 3a \\ = 4a[/tex]

[tex]\large\mathfrak{{\pmb{\underline{\orange{Happy\:learning }}{\orange{.ඞ}}}}}[/tex]

Answer:

Step-by-step explanation:

a+3a

since they are like terms u can add them

=4a  

therefore a+3a=4a