[tex]x + 2x + 3x + ... + 100x = 50500[/tex]
[tex]x(1 + 2 + 3 + ... + 100) = 50500[/tex]
[tex]x \times \frac{100(100 + 1)}{2} = 50500[/tex]
[tex]x \times \frac{100 \times 101}{2} = 50500[/tex]
[tex]x \times 50 \times 101 = 50500[/tex]
[tex]x \times 5050 = 50500[/tex]
[tex]x = \frac{50500}{5050} [/tex]
[tex]x = 10[/tex]