Basic Mathematics
# Ratio, Rate, and Proportion

$ABC$ and $DEF$ in the above figure are similar, where the corresponding side of $\overline{AB}$ is $\overline{EF}.$ If $\lvert{\overline{AC}}\rvert=3,$ $\lvert{\overline{AB}}\rvert=4$ and $\lvert{\overline{DE}}\rvert=l=18,$ what is the length of $\overline{EF}?$

Two right triangles