cross-multiply

English

Etymology

cross- +‎ multiply

Verb

cross-multiply (third-person singular simple present cross-multiplies, present participle cross-multiplying, simple past and past participle cross-multiplied)

1. To set the product of the extremes of a proportion equal to the product of its means.

   Cross-multiplying $3/5=x/2$ yields $3\times 2=5x$.

Further reading

• cross-multiply on Wikipedia.Wikipedia