Given that x^2+ax+b=(x-7)^2-a work out the values of a and b

I have got upto x^2-14x+49-a but idk how to get to the answer from there?! please help?!

x^2 + ax + b = (x - 7)^2 - a

x^2 + ax + b = x^2 - 14x + 49 - a

Look at the x terms: a = -14

Look at the constant terms: b = 49 - a so b = 63

x² + ax + b = x² - 14x + 49 - a

ax + b = -14x + 49 - a

a = -14 and b = 63