Saving values to variables

What code do I need for a program to take user inputted # values and save them to variables so I can use them later in the program? I want it to take the variables and compare them.

if var1, var2, var3 >=30 then
...

You can use 'read()' to get input from users
You can use 'tonumber()' to convert a string into a number

local num1 = tonumber( read() )

As for comparisons

if var1, var2, var3 >= 30 then

would not work. you would have to do this

if var1 >= 30 and var2 >= 30 and var3 >= 30 then