3v-5=d
In this case, v is proportional to d. Meaning that as you increase the value of v, then the value of d will change at a proportional rate. For example, if v was 1 then d would be -2. Then if v was 2 then d would be 1. If v was 3 then d would be 4. The value of d increases 3 for every increase in v. Does that help?
