In 11 years, the age of Russel will be half of the square of the age he was 13 years ago. Find his present age. Explain your solution
Let x be his present age.
x + 11 = (1/2)(x - 13)^2
You could solve that quadratic equation or use trial and error.
Try x = 21
does 32 = (1/2)*8^2 ?
Looks good to me.