The flow of calculations is from top to bottom and from left to right. A variable is defined from the point it is assigned a value and below that point.

A variable is assigned a value using the ":=" operator. The flow of this operation is from right to left. For example mass := 10.5 lb assigns a value to the variable "mass".

The value of a variable can be displayed using the "=" operator. The flow of this operator is from left to right. For example mass = 5 kg shows the value of the variable mass.

The two operators above can be combined like this: mass := 10.5 lb = 4.763 kg. This also shows MathCAD's ability to convert between units. We input the value 10.5 lb, MathCAD converts it to kg and displays that value.

MathCAD uses SI units internally. All units that you input are automatically converted to the corresponding SI unit before calculations are performed.

To find the derivative of the temperature decay I used the symbolic solve operator, →, a right arrow. This produces a symbolic result rather than a numeric one.

That's it. You should be able to make sense of the worksheet with this information. Let me know if there are still questions.