(√3-√5)(√5+√3)/(7-2√5)=(3-5)/(7-2√5)=
-2/(7-2√5)=-2(7+2√5)/((7-2√5)(7+2√5)=
-2(7+2√5)/(49-20)=-2(7+2√5)/29=
-14/29-4√5/29=-0.7912 approx.
The question could be interpreted differently: ((√3-√5)(√5+√3)/7)-2√5.
The solution is -2/7-2/√5=-2/7-2√5/5=-2(5+7√5)/35=-1.1801 approx.