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 2 signes in often use ofwel which the first kan zijn made thus + and betokeneth more: the other kan zijn thus made − and betokeneth https://postheaven.net/crowncarbon6/het-feit-over-aluminium-kozijn-wrapfolie-dat-niemand-voorstelt