exeng
From FL350, you'll travel about 85nm. At Vmd (ca 240kt IAS), you'll set off at about 410kt TAS. By FL150, your TAS will have dropped to about 300kt. For tha complete descent your average TAS will decrease from about 7nm per min at TOD, down to 4 nm per min as you reach the Indian Ocean.
You'll do those 85 miles in about 15 mins.
At Vmd.