Math solver thing

-- Some math solver thing
-- Not sure what kind of math it is but it solves it

function removedec(number)
    kek = number
    local strnum = tostring(number)
    for i=1,#strnum do
        if string.sub(strnum,i,i) == "." and string.sub(strnum,i+1,i+1) == "0" and string.sub(strnum,i+2,i+2) == ""  then
            kek = tonumber(string.sub(strnum,1,i-1))
        end
    end
    return kek
end

function solve(tab)
    local bab = {}
    for i=1,#tab do
        local num = tab[i]
        local neg = false
        num = num/2
        if num < 0 then
            neg = true
            num = num * -1
        end
        if neg == true then
            sum = i.."    |    ".."(x-"..removedec(num)..")²    |    C  :  "..removedec(num*num)
        else
            sum = i.."    |    ".."(x+"..removedec(num)..")²    |    C  :  "..removedec(num*num)
        end
        table.insert(bab,#bab+1,sum)
    end
    for i=1,#bab do
        print(bab[i])
    end
end

solve({15})