Arithmetic with variables

Is there no way to do arithmetic with variables in CL? For example, if I have

a = exp1.numericValue
b = exp2.numericValue

I want to be able to do something like

c = a + b
content: “The sum of the two numbers you entered is ${a} + ${b} = ${c}”.

but that does not work. This seems like very basic functionality that I would expect the Computation Layer to have; am I overlooking something obvious?

I would use simpleFunction and Evaluate for that.
something like this work for you?

This works. Thank you!