### Order of operations

Parenthesis, Exponents/Power, Multiplication, Division/Modulus, Addition, Subtraction

Notation example

(a^{2} * b) + c – d

1. a^{2}

2. * b

3. + c

4. – d

### Proportions

`a / A = x / X`

a | b | |

— | = | — |

A | B |

You’re trying to solve x. You have to cross-multiply. Be mindful of order of operations.

`x * A = a * X x = a * X / A`