What is Polaris? A. It is fusing hydrogen at its core.
B. It has lost its outer shell and retained only a hot core that is slowly losing its brightness.
C. Its temperature has decreased, but it is shining brighter than before.

wire in brush may conduct electricity from cell to drill and vice versa electrc shock possible

i think the answer would be reserve.

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form