冬鱼的快乐

n :  the number of times you go out for  a walk {0,1,2,…,7};

x1*10+x0 : your real age, without consideration of the month, and
                   x1={0,1,2,...,9}; x0={0,1,2,...,9};

a2*100+a1*10+a0 : the number after all of the calculaitons

according to the calculation procedure, we become following equation:

(n*2+5)*50 + [1753,1754] - (2004-x1*10-x0) = a2*100+a1*10+a0;

=>
n*100 + 250 + [1753,1754] – 2004 + x1*10+x0 =  a2*100+a1*10+a0;

=>

n*100 + [1753+250-2004, 1754+250-2004] + x1*10+x0 = a2*100+a1*10+a0;

=>

n*100 + [-1, 0] + x1*10+x0 = a2*100+a1*10+a0;

=>
n = a2,
the number of times you go out for a walk;

x1*10 + x0 + [-1,0] = a1*10+a0;
depending on the month of birthday,
if your birthday is already passed by, then
x1*10 + x0 = a1*10+a0;
else
x1*10 + x0 -1 = a1*10+a0;
over!:P