The function f(x) has the property that if P and Q are any two distinct points on the graph of y = f (x), then the slope of PQ is equal to 1. What is the value of f(10) - f(0)?
\(\phantom{twice the sum of the $x$-coordinates of $P$ and $Q.$}\)
[ f(10) - f(0) ] / [ 10 - 0 ] = 1
[f (10) - f(0) ] / 10 = 1
f(10) - f(0) = 10 * 1
f(10) - f(0) = 10
