(x-5)(x-4)-(x+1)(x-2)=7

$$\eqalign{
& \left( {x – 5} \right)\left( {x – 4} \right) – \left( {x + 1} \right)\left( {x – 2} \right) = 7 \cr
& \Leftrightarrow {x^2} – 5x – 4x + 20 – {x^2} + 2x – x + 2 – 7 = 0 \cr
& \Leftrightarrow – 8x + 15 = 0 \cr
& \Leftrightarrow x = {{15} \over 8} \cr} $$