Find the solutions
x^2=16x-28

Minus 16x both sides and add 28 to both sides
x^2-16x+28=0
factor
hmm, what 2 numbers multiply to 28 and add to -16
hmm
1 and 28? nope
2 and 14? yep
since middle term is negative and last tem is positive, both of the factors are negative

(x-14)(x-2)=0
set each to zero
x-14=0
x=14

x-2=0
x=2

x=2 and 14

Letter a i would say