Algebra
# Properties of Arithmetic

$\left ( 1 + \frac{1}{ \color{#D61F06}{4}} \right ) \left ( 1 + \frac{1}{\color{#D61F06}{5}} \right ) \left ( 1 + \frac{1}{\color{#D61F06}{6}} \right ) \left ( 1 + \frac{1}{\color{#D61F06}{7}} \right )$

Evaluate the expression above.

What is $a - (a - b - a - c + a) - b + c?$