Answer:
Year of death was 1727 at age 84
Explanation:
Let my current age was X
Newton was appointed chair when I was (1/ 3)X - 2 old
Eighteen years later
18 + (1/3) X - 2 = (1/2) X + 2
16 -2 = (1/2 -1/3)X
14 = (1/6) X
84= X
The age of death is 1699 + 1/3 X
1699 + (1/3) * 84
1699 + 28
1727