Distributions of 3220 RGBs (left panels) and 3276 RCs common to LAMOST and Kepler (right panels) on the τ–∆τ/τ plane. Here, τ and ∆τ are the estimated ages using the isochrone fitting method and their associated uncertainties. The red dot presents the median value in each age bin with a bin size of 1.0 Gyr. Green dots are stars with M < 0.7 M_⊙. Blue star symbols show post-mass-transfer helium-burning stars identified by Li et al. (2022b). Distributions of ages and their associated uncertainties are over-plotted using histograms.