I need help with this question please

 
Supposed you know that Ls and LY are complementary, and that mLS=3(mLY)-90°

The value of mLY is

Someone help me with this question!!

I need help with this question please Supposed you know that Ls and LY are complementary and that mLS3mLY90 The value of mLY is Someone help me with this questi class=