Metabolic rate to joules

Q. For a person with a resting metabolic rate of 1600 Calories in 24 hrs calculate their resting metabolic rate in Watts (joules per second)

* an explanation and formula would be sooooooooo helpful

Assuming calories with a lower case “c” (a capital “C” indicates food calories = 1000 calories-lower case), then:

1 cal = 4.186J
1600 cal = 1600(4.186J)
= 6700J

Over 24 hours (86,400s):

E = 6700J/86,400s
= 0.078W