let f be the force of air resistance. for upward motion f acts downward.

let a1 be retardation

mg+f=ma1

for the downward motion f acts upward.

let a2=downward acceleration

mg-f=ma2

a2=g-f/m

thus, a1>a2

therefore t1<t2

because h=(a1.(t(to the power 2)))/2

also h=(a2.t2to thepower2)/2