What is the value of the expression of -(-4)

Grandma made an apple pie. josh and his brother joe finished 4/5 of it. then 3 friends came over and shared the left over. how much pie did each friend eat

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'

The graph of the the function f(x) is given below. find [tex]\lim_{x \to 0\zero} f(x)[/tex] [tex]\lim_{x \to 1+\oneplus} f(x)[/tex] [tex]\lim_{x \to 0-\zeroneg} f(x)[/tex]