Answer: 91.592
Step-by-step explanation:
Start by distributing -5x into x then into -3y. So -5x times x equals -5x^2( -5x squared), then -5 times -3y, equals 15xy so your answer is -5x^2 + 15xy.
You would have no problem at all if it said "7 cows minus 2 cows", or "7 books minus 2 books". The THINGS just happen to be m's instead of cows or books.
If you have a calculator, you can use the inverse cos " cos⁻¹ " key. Many upper level books write that as Arccos so as not to confuse you with a negative exponent. We do that because if you take the cosine of any angle, and then the inverse cosine of any angle, it leads you back to the original angle. Think of it as a big "UNDO" button.
To one decimal place, that result is 61.6 degrees.