Simple substitution
Algebra uses letters to stand for variables or unknown amounts. If we know or can find out the value of that letter, we can substitute (replace) the letter with its numerical value, and then work out the value of the whole expression.
Substitution is a word most commonly associated with football and other sports  players are replaced with someone in the same position (usually). Think about this to help you remember what substitution means. You need to remember that algebra is written in a particular way, and especially that the expression "3x" actually means "3 lots of x" or "3 times x". e.g. If x = 5, the value of 3x is 3 x 5 = 15, and the value of 6x = 6 x 5 = 30. In algebra, any letter can be used to stand for the unknown amount or variable, and you might sometimes get two unknowns in one expression. e.g. If a = 2 and b = 3, then the value of a + b is 2 + 3 = 5. 
Video tutorials 

Nothing here yet? Check out my YouTube channel for all videos that are currently available. Video tutorial for this topic coming soon!
Extra videosA couple of simple examples from Jason Henstridge

Learn more
Test yourself!Nothing yet  check back again soon!
