How Do I Do This Chemistry Equation?

This question was answered here, but I believe there was some confusion of units.

A problem of this sort is really just a problem in units conversion. Any units conversion is a multiplication by a specially chosen form of "1." For example, 1 liter = 10 deciliters, so (10 dl/1 l) = 1. Units in an expression work just like any other variable: They can be multiplied and divided. However, when you do addition and subtraction (not needed in this problem), you need to make sure you're only adding or subtracting things that have exactly the same units. (You can't subtract 3 inches from 4 gallons, for example.)

Since we are given mg and dl, we need to somehow find values for "1" that will let us end up with g and "human." Milligrams to grams is an easy conversion, but deciliters to "human" needs a little more thought. For that, we use the given conversion that 4.7 liters = 1 human (in terms of blood volume).

(130 mg/dl)*(1 g/1000 mg)*(10 dl/1 l)*(4.7 l/human) = (130)(10)(4.7)/1000 g/human
= 6.11 g/human