in pipeline A, first instruction executes in 16ns (8stage*2ns). after that each 1 instruction get completed in 2ns.
so total delay is 1*16 + 99*2 = 214ns
in pipeline B, first instruction executes in 15ns =(3+3+3+3+3). after that each one instruction get completed in 3ns. (as delay of pipeline is maximum delay of any stage)
so total delay is 1*15 + 99*3 = 297 + 15 = 312ns
so time saved is 312 - 214 = 98 ns