If a relationship exists between two variables such that their ratio is a

non-zero constant, the relationship is referred to as a **direct variation**.

The constant is often referred to as the

**constant of variation**, or constant of proportionality.

If two variables, say *x* and *y*, are in direct variation, then *y* = k*x* for some constant k.

In this relationship, we say *y varies directly with x* or *y varies directly as x*.

Since

*y* varies directly with

*x*, the relationship can be represented by an equation of the form

*y* = k

*x*, where k is some constant.

The constant, k, is referred to as the constant of proportionality.

Use the given values to solve for k.

*y* | = | k*x* |

16 | = | k(8) |

16 ÷ 8 | = | k(8) ÷ 8 |

2 | = | k |

Since

*y* varies directly with

*x*, the relationship can be represented by an equation of the form

*y* = k

*x*, where k is some constant.

The constant, k, is referred to as the constant of variation.

Use the given values to solve for

*x*.

*y* | = | k*x* |

14 | = | 2*x* |

14 ÷ 2 | = | 2*x* ÷ 2 |

7 | = | *x* |