The sum of the odd numbers from 1 through 49 is S. The value of S is:
1+3+5+7+9+11+13+15+17+19+21+23+25+27+29+31+33+35+37+39+41+43+45+47+49=625
The sum of the even numbers from 2 through 48 is E. The value of E is:
2+4+6+8+10+12+14+16+18+20+22+24+26+28+30+32+34+36+38+40+42+44+46+48=600
Therefore S is greater than E. Their difference is 25, hence:
S=625 and E is 600.
625-600=25
.