Respuesta :

[tex] \bf\green{7.8 \times c + 3.4 = 19} \\ \\ \bf\red{7.8 \times 2 + 3.4 = 19} \\ \\ \blue{\bf{15.6 + 3.4 = 19}} \\ \\ \bf \red{\boxed{ \underline{\underline{\pink{ 19 = 19}}}}}[/tex]

Haha, very easy... :)