Answer:
I can help with Q "4" as -
It uses triangle congruence test - here we use - SAS, as
one side is equal as it is given
both the angles are 90 degree
and they share a same side
so -
8x = 6x + 5
8x - 6x = 5
2x = 5
x = 2.5
RU = 6x+ 5 = 6 (2.5) + 5 = 20
( I am not so sure but I think this is the answer )
