Sorry I can't solve it.
Firstly, the equation is wrong. It is supposed to be <span>81 ≠ </span><span>30.25
Second of all, this is the best I got </span>81= <span><span>−<span>76 <span>(<span>cos<span>(r) </span></span></span></span></span>+ <span>106.25</span></span>
the answer is 
subtract 6x on both sides → 
divide both sides by -2y → 
Answer:
I think it 7 ok ok ok ok ok ok