QR is 12, as you establish a proportion: 21/14 = x/8, then cross-multiply to obtain 14x = 168, which you solve by dividing to find x = 12.
Answer: Fourteen students are not enrolled in any foreign languages.
Step-by-step explanation: Begin with the total student count and subtract the number enrolled in each language class. This yields 19 for French, 12 for Spanish, and 7 for those taking both. Summing these numbers gives 38. Next, repeat this process, subtracting each category from 30 to find how many students are not participating in either language. You would end up with 11 for French, 18 for Spanish, and 23 for both. Adding these values results in 52. Finally, subtract 38 from 52 to arrive at the final result of 14.