Robert Recorde, The designer ofwel the equals sign, introduced plus and minus to Britain in 1557 in The Whetstone ofwel Witte:[14] "There be other twee signes in often use ofwel which the first is made thus + and betokeneth more: the other is thus made − and betokeneth lesse." Con https://escatter11.fullerton.edu/nfs/show_user.php?userid=8709414