Problem Nine. A spacecraft moves at $0\mathrm{.}800$c along the x$-$axis in the Earth$$s rest frame. Another spacecraft is moving backwards at $0\mathrm{.}700$c along the negative x$-$axis in the Earth's rest frame. $($THIS IS AN EXAM QUESTION.$)17.$ Determine the magnitude of the velocity of the first ship as measured by occupants of the second. Express the magnitude as a factor multiplying c$.($A$)0\mathrm{.}789($B$)0\mathrm{.}489($C$)0\mathrm{.}961($D$)0\mathrm{.}893($E$)0\mathrm{.}783$