In the US, Australia, Canada, Egypt, Mexico, Portugal, Philippines and Saudi Arabia the notation is: y = mx + b
In the UK, Australia (also), Bahamas, Bangladesh, Belgium, Brunei, Cyprus, Germany, Ghana, India, Indonesia, Ireland, Jamaica, Kenya, Kuwait, Malaysia, Malawi, Malta, Nepal, Netherlands, New Zealand, Nigeria, Pakistan, Peru, Singapore, Solomon Islands, South Africa, Sri Lanka, Turkey, UAE, Zambia and Zimbabwe: y = mx + c
In Afghanistan, Albania, Brazil, Catalonia, Czech Republic, Denmark, Ethiopia, France, Lebanon, Holland, Kosovo, Kyrgyzstan and Viet Nam: y = ax + b
In Azerbaijan, China, Finland, Russia and Ukraine: y = kx + b
In Greece: ψ = αχ + β
In Italy: y = mx + q
In Japan: y = mx + d
In Latvia: y = jx + t
In Romania: y = gA + C
In Sweden: y = kx + m
In Slovenia: y = kx + n