Opposite numbers - Zero sum 7. a) Write the opposite of each of the
following numbers:
+16 ; -2.5; -14 ; 0 ;
2.8 ; -100 ; -0.9 .
b) Which of the following sums is zero?
-32 + 23; -32 + (-32) ; 2.4+(-2.4);
-9.05 + 9.5; -1 + 1 ; -3001+3001.
Addition of numbers​

When i did the math i got 11 cm

Look, when you want to do something like put it like x^2. x2 could mean x² or x₂. so to clear confusion, know the notation. to find the product multiply the x's and you get -8x and the y's and you get 6y. since it's all being multiplied it is just -8x6y, or answer a. although the better answer is -48xy(combining -8 and 6) because you should multiply constants whenever you can.