Respuesta :

The 7+9+11+13+15 it’s like 2 by two.
You are doing 7+9+11+13+15+17+19+21+23+25+27+29+31+33+35+37+39+  41+43+45+47+49+51+53+55+57+59+61+63+65+67+69+71+73+75=1435