NPP at first trophic level would be the GPP for second trophic level. NPP at second trophic level would be GPP for third trophic level. Therefore, 100x(kcal∕m2∕yr) would be GPP at second trophic level and 100x×10%(kcal∕m2∕yr) i.e., 10x(kcal∕m2∕yr) energy would be GPP at third trophic level.