the complete question in the attached figure
we know that
in the triangle BDC
cos alfa=3/y----------> equation 1
sin alfa=x/y----------> equation 2
in the triangle ABD
cos alfa=4/5--------> equation 3
sin alfa=3/5---------> equation 4
then
Equal equation 1 and 3
3/y=4/5---------> y/3=5/4----------> y=15/4
Equal equation 2 and 4
x/y=3/5-------> x=3*y/5------------> 3*15/(4*5)-----> x=9/4
the answer is
x=9/4 y=15/4
