Write the number 10/25 as a decimal and describe the process

10 divided  by 25 is 0.4
You have to ind the reciprocal of the number

if 25 *2=50 then 25*4=100 then do 10*4=40 so the decimal is 0.40

Annual Social Security benefit = 0.42 x $37,991 = $15,956.22
Annual bills = $1,755 x 12 = $21,060
Outstanding annual bill to be settled after using the Social Security benefit = $21,060 - $15,956.22 = $5,103.78
Monthly supplementary money needed = $5,103.78/12 = $425.32