निम्नलिखित विकल्पों में से कौन सी एक बुनियादी गणितीय अंकगणितीय संक्रिया (operation) नहीं है?

There are five spools of thread in white, black, red, green, and blue colors. Each spool measures 87.50 m. If thread used is: white = 43.25 m, red = 38.62 m, black = 71.98 m, green = 21.04 m, and blue = 29.74 m, find the balance thread remaining in all five spools together.

A government office uses 4 reams of paper daily. How many reams in total will they use in 7 days?