Question

Find the ratio of each of the following in simplest form:
$$15\ mm$$ to $$2\ cm$$

Answer 1

$$15\ mm: 20\ cm$$
$$10\ mm: 1\ cm$$
$$15\ mm=\dfrac {15}{10}\ cm$$
$$\dfrac{\dfrac{15}{10}}{\dfrac 21}=\dfrac {15}{10}\times \dfrac12=\dfrac 34=3:4$$