So |x+7/2|+|y-4/3|=0.

Because the sum of non-negative numbers is 0,

So |x+7/2| and |y-4/3| are all equal to 0.

That is, x+7/2=0 y-4/3=0.

So x =-7/2 and y = 4/3.

So 2x+y=- 17/3.

The second question should be discussed in categories.

1。 When a, b and c are all greater than 0

2。 a & gt0，b & gt0，c & lt0

3.a & gt0b & lt； 0，c & lt0

And so on, there are many situations, you should understand?