I, Sir Isaac Newton, was appointed to the Lucasian Chair of Mathematics at Cambridge University two years before 1/3 of my life had passed, Eighteen years later, two years after 1/2 of my life had passed, I published Principia. I become master of the Royal Mint in 1699 and held that position for the final 1/3 of my life.
When did I die and how old was I?

Year of death was 1727 at age 84

Step-by-step 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

4a. is 3 miles every hour

4b. is 1/3 of an hour per mile

step-by-step explanation:

$5.41

step-by-step explanation:

$20 - $14.51 = $5.49.