- 18 + 21 △ 7 × 1 / 7

- 18 + 21 △ 7 × 1 / 7


-18+21÷(-7)×1/7
=-18-3×1/7
=-18-3/7
=-129/7



Two thirds minus x divided by seven eighths equals four twelfth,


(⅔-X)÷⅞=4/12
⅔-X=8/21
X=5/21