$$ 2 + 2 = 4 $$ $$ {:nonum:} 3 + 3 = 6 $$ $$ 4 + 4 = 8 $$

Equation (1)
Source
$$ 2 + 2 = 4 $$

(1)

Equation
Source
$$ 3 + 3 = 6 $$

Equation (2)
Source
$$ 4 + 4 = 8 $$

(2)