mml=<math xmlns="http://www.w3.org/1998/Math/MathML"><mstyle mathsize="12px"><mrow><mfenced><mrow><msub><mi mathvariant="normal">ϕ</mi><mn>1</mn></msub><mo>+</mo><msub><mi mathvariant="normal">ϕ</mi><mn>2</mn></msub></mrow></mfenced><mo>/</mo><msub><mi mathvariant="normal">ε</mi><mn>0</mn></msub></mrow></mstyle></math>