An equation is a math sentence made up of numbers, symbols, and operations that has an equals sign and a correct answer.
For example:
7y + [tex] \frac{8}{5} [/tex] = 6[tex] m^{2} [/tex]
An inequality is a math sentence made up of numbers, symbols, and operations that has an inequality symbol.
For example:
7 + u > 5x
An expression is a math sentence made up of numbers, symbols, and operations.
For example:
4h + 77 (5 - [tex] b^{2} [/tex])
Hope that helped! =)