Question

t=2-2[2r-(1-r)] , .

Answer 1

2-2(2r-(1-r))
primero se resuelve los paréntesis
2-2(2r-1+r)
2-4r+2-2r
4-6r
2-3r=0
-3r=-2
2=3r
2/3=r

Answer 2

t=2-2[2r-(1-r)] =2-2[2r-1+r]=2-2(3r-1)=2-6r-2
t=-6r