(2a- 1)+(5b-4)=0 From the formula, we can know that:

2a- 1=0，5b-4=0。

Found: a= 1/2, b=4/5.

The inverse of (1)a is-1/2, and the inverse of B is -5/4, so their sum is.

(- 1/2)+(-5/4)=-7/4

These are brackets. You should understand the score.

(2)(- 1/2)+(-5/4)= 1/2+5/4=7/4

The brackets here are symbols representing absolute values.

2. (1) 2+1.5-5.5 =-2 (km)

Note: The origin of code A is 0, the east is positive and the west is negative, so the east is represented by positive numbers and the west is represented by negative numbers. Here, it is 2 kilometers east to the wholesale department B, so it is represented by 2, and then it is 1.5 kilometers east to the shopping mall C, 1.5 kilometers east and 5.5 kilometers west, so it is represented by (-5.5). All together, it is (-2) kilometers, that is to say, supermarket D is 2 kilometers west of freight yard A.

(2)2+ 1.5+5.5=9 (km)

Calculate the total distance, regardless of the direction, just add up the values directly.

Remember to answer the application questions.