5a + 650
при a = 13:
5 * 13 + 650 = 65 + 650 = 715
при a = 15:
5 * 15 = 75 + 650 = 725

Вычисления:
$\snippet{name: column_multiplication, x: 13, y: 5}$
 
$\snippet{name: op_column, sign: '+', x: '650', y: '65', z: '715 '}$
 
$\snippet{name: column_multiplication, x: 15, y: 5}$
 
$\snippet{name: op_column, sign: '+', x: '650', y: '75', z: '725 '}$

16(b − 13)
при b = 13:
16 * (13 − 13) = 16 * 0 = 0
при b = 28:
16 * (28 − 13) = 16 * 15 = 240

Вычисления:
$\snippet{name: column_multiplication, x: 16, y: 15}$