Respuesta :

Answer:

d=3

Step-by-step explanation:

13d=39

d=39/13

d=3

Hello!

6d + 7d = 39 <=>

<=> 13d = 39 <=>

<=> d = 39 : 13 <=>

<=> d = 3 => 6 × 3 + 7 × 3 = 39

Good luck! :)