Maximum bending moment in simply supported beam under equally spaced in the middle uniform load.
Bending moment
$$ M_{B_{d_{max}}} = {\left({ {W_d \over 4} }\right) \cdot \left({ 2 \cdot a + b - {b \over 2} }\right)} $$
Bending moment of simply supported beam subject to two equal loads at equal distance from supports.
Bending moment
$$ M_{B_2p} = {P \cdot a} $$
Combined maximum bending with 2 equal point loads and distributed load.
Combined bending moment
$$ M_{B_{2pd}} = {M_{B_{d_{max}}} + M_{B_2p}} $$