Inverting OP AMP SLEW RATE
Triangular wave amplitude: 500mV
  Triangular wave frequency: 11 kHz
  The op-amp should have a gain of 6.


500mV seems to be peak to peak (Vpp) since you input 250mV in the amplitude field.

Output 6*0.5Vpp = 3Vpp

Period = 1/11k = 90.9µs

dv/dt = 3V per one half period = 66000V/s = 0.066 V/µs so your measurement is correct.


  The red wave(channel A) output is from the op-amp with slew rate of twice the minimum slew rate and the blue wave(channel B) output is from the opamp of one-fifth of the minimum slew rate. Is this simulation output correct?
  also, what can i say to discuss the differences between simulation results that indicate slew rate distortion is taking place.


Yes, it looks correct, but I wonder why the question specified a triangle wave while a square wave (or a sine) would make it a lot more obvious and easier to understand. I mean, an opamp which is limited by its slew rate will output a triangle wave, so if you input a sine or a square and you get a triangle at the output, then you know it's happening. If you input a triangle at the input you will get a triangle at the output anyway, so you have to check if the amplitude and phase are correct to know if it is slewing, which is more complicated.

See this article for examples of slew rate distortion.