Displaying a hyphen"-" from a xml to Corona?

I have a xml file that has a hyphen"-" inside, how can I display the hyphen into the Corona apps?

Part of the xml file:

<data>Value : 54-57</data>

For now I can only display 5457 which became totally wrong.

Parts of the code for xmlparse:

print("found item")
if founditem == true then
    for i=1,#Item do 
        for j=1,#Item[i].child do
            if Item[i].child[j].name == "data" then
                ValueReading[i] = simplifyData(Item[i].child[j].value)
            end
        end
    end 
end

Parts for the "SimplifyData" code:

function simplifydata(data)
data = string.gsub(data,"%a", "")
data = string.gsub(data,"%s","")
data = string.gsub(data,":","")
data = string.gsub(data,"-","")

data = tonumber(data)
return data 
end

Any ideas how can I make the hyphen display? Thanks