Yes, you can add a negative and a positive when doing like terms.
It will be 69 because 68 is wrong and 69 is right
It is important to remember that weight is not the same as mass - the weight of an object and its mass are directly proportional . This means that for a given gravitational field strength, the greater the mass of the object, the greater its weight.
1/4+1/4=1/2 so the two friends get 1/4 of the pineapple.
Hope this helps :) <span />
