Two spaceships are approaching one another. According to observers in our frame,

(a) the left-hand ship moves to the right at \((4 / 5) c\) and the right-hand ship moves to the left at \((3 / 5) c\). How fast is the right-hand ship moving in the frame of the left-hand ship?

(b) the left-hand ship moves to the right at speed \((1-\epsilon) c\) and the right-hand ship moves to the left at \((1-\epsilon) c\), where \(0<\epsilon<1\). How fast is the right-hand ship moving in the frame of the left-hand ship? Show that this speed is less than \(c\), no matter the value of \(\epsilon\) within the range allowed.