Estimate the sum to the nearest tenth: (-2.678) + 4.5 + (-0.68)

(-2.678) + 4.5 + (-0.68)= 1.142
since .1 is in the tenth place and 42 isnt greater than 50, the answer would be 1.1. 

The best thing that would first be done in the aspect would be to first sum up the numbers that are in parenthesis.

Let's keep in mind that a (-)+(-) would equal a positive. This would mean that a negative number, plus another negative number would then be a positive number.

Your  1.14200 

Sin(a)+cos(a)+cot(a)-1=2(csc(x)+1)