A conversion factor is a number used to change one set of units to another, by multiplying or dividing. When a conversion is necessary, the appropriate conversion factor to an equal value must be used. For example, to convert inches to feet, the appropriate conversion value is 12 inches equal 1 foot.
Answer:
t = 
Step-by-step explanation:
Given
D = M + Mrt ( subtract M from both sides )
D - M = Mrt ( divide both sides by Mr )
= t