Substitution

Substitution | Algebra | Maths | FuseSchool In algebra, we replace a letter with numbers in the process known as substitution. Given the formula A = 1/2bh, if the base is 5cm and the height is 10cm, then the area is ½ X 5 X 10 because we have replaced the b with 5 and the h with 10. You just need to be be careful with negative numbers: it is best to use brackets when calculating with negatives.