Respuesta :

0.05n + 0.1d = 5.15
n = d - 8

0.05(d - 8) + 0.1d = 5.15
0.05d - 0.4 + 0.1d = 5.15
0.15d = 5.55
d = 37

Check:
0.05(29)+ 0.1(37)= 5.15
1.45 + 3.70 = 5.15
5.15 = 5.15 :)