Question 1147629
{{{x+10=(x-10)^2}}}

{{{x+10=x^2-20x+100}}}

{{{x=x^2-20x+90}}}

{{{x^2-21x+90=0}}}



2*45=2*5*3*3=15*6

{{{(x-6)(x-15)=0}}}


{{{highlight(x=15)}}}
Because x=6 will not work.
Age ten years ago must be non-negative.