Respuesta :

Answer:

answer given in step by step...

Step-by-step explanation:

13x+13(x+1)+13(x+2)=312

13x+13x+13+13x+26=312

39x+39=312

39x=312-39

39x=273

x=7

first number=13x=13*7=91

second number=13(8)=104

third number=13(9)=117