What is the result of adding 20 to -20?

Seth practice piano for 1 1/3 hours on saturday and 5/6 hour on sunday for much longer did he practice on saturday than on sunday?

Add the fractions, and simply the result to lowest terms. 2/3 + 2/7= ?

Give the functions f(x) = |x + 2| - 3, what is the domain? a, b,c, or d all real numbers x > 2 x < -2 all real numbers and x cannot equal to 2