Eight and one six minus 7 and three forths

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

Ametal rod needs to be 9 feet and 5.5 inches in length. the sections of the poles being used are each 1 foot and 10.5 inches long. how many 1ft 10.5in sections would be needed to complete the 9ft 5.5in metal rod? and how many inches of material will be left?

Write a function for a rotation 90 degrees counter clockwise about the origin, point 0