Answer
12
Work Step by Step
$x^{2}-7x+4$, for $x=8$, substitute 8 for each 'x'
$8^{2}-7\times8+4$, using order of operations, complete exponents first
$64-7\times8+4$, then multiplication and division in order left to right
$64-56+4$, then addition and subtraction in order left to right
$8+4$, any remaining addition and subtraction left to right
$12$
