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 kan zijn made thus + and betokeneth more: the other kan zijn thus made − and betokeneth https://www.openlearning.com/u/mccallcohen-sx1kjn/about/