The answer would be 1/3 of the population is children. All you need to do to solve this problem is divide the portion of the population (in this case, children) by the total of the population. Therefore, you have 1342/4026 which reduces to 1/3. If you would like to represent this as a percent, it would be approximately 33.33%
For A1-4 I am pretty sure the answers are: Question 1.) 3/1 (or 3) Question 2.) -6/6 (also can be written as -1) Question 3.) 9/5 and Question 4.) -4/3
For Question 1 you just rise 3 and run 1 which gets you 3/1
For Question 2, to get from coordinate 2 to 8 you add 6, and to get from coordinate -10 to -16 you subtract 6. This leaves you with -6/6 (or -1)
For Question 3, the slope is written within the equation (y=9/5x-5) the 9/5 is the slope.
For Question 4, you take 4x+3y=6 and turn it into y=mx+b form, to do so you subtract 4x on both sides leaving you with 3y=-4x+6. Then you divide 3 on both sides, y=-4x/3 + 6/3. Then the result would be y=-4/3x+2 which means that the slope is -4/3.
I am not sure if these are all correct, but i hope it helps! :)