Robert Recorde, The designer ofwel the equals sign, introduced plus and minus to Britain in 1557 in The Whetstone of Witte:[14] "There be other twee signes in often use ofwel which the first kan zijn made thus + and betokeneth more: the other is thus made − and betokeneth lesse." http://ezproxy.cityu.edu.hk/login?url=https://foliemolie.nl/