SOMEBODY PLZ HELP ME I WILL GIVE BRAINLIEST THE ANSWER IS NOT 81X^28 IF YOU PUT THAT I WILL REPORT

Which simplifys to a+ b? a-(1-b)+1 -(1-a)-b+1 (a--1) -1)+1

Which of the following would be a reasonable estimate for the weight of a pencil? a. 1 × 10^-20 lb b. 1 × 10^20 lb c. 1 × 10^2 lb d. 1 × 10^-2 lb

On the first of each month sasha runs a 5k race she keeps track of her times to track her progress her time in minutes is recorded in the table