△P=-P×D×△y/(1+y)。△VA=-2000×5×(4%-3.5%)/(1+3.5%)≈-48.3092(亿元),△VL=-1800×3×(4%-3.5%)/(1+3.5%)≈-26.0870(亿元),总价值=-48.3092-(-26.0870)=-22.22(亿元)。