I need help bad it’s like son 2 way table stuff

The first one I'll do is Physics because you know the amount of girls and total amount of students. Use the equation x+19=33. Note that x is the amount of boys we are trying to find. All you need to do is simply subtract 19 from both sides to get x alone.

                                             x + 19 = 33

                                                  -19   -19

                                             x         = 14

For the total that's going up and down, you can do this same process again, but just using x for girls instead of boys. Your equation should look like 47+x=80. Once again, subtract 47 from both sides.

                                             47 + x = 80

                                             -47        -47

                                             x         =  33

Now you can find whole row for boys. This equation will be a little longer, but it's still pretty easy. 18+x+14=47 is what we will be using. We first will need to combine like terms (the 18 and 14), then subtract it off from both sides to get x alone.

                                             18 + x + 14 = 47

                                                    x + 32 = 47

                                                        -32   -32

                                                     x         = 15

Moving onto the biology column, we'll be using the equation 15+x=21

                                             15 + x = 21

                                            -15        -15

                                             x         = 6

Now we can find out the girls column with this equation: x+6+19=33

                                           x + 6 + 19 = 33

                                           x + 25      = 33      

                                               -25         -25

                                                     x      = 8

Lastly, we can find the chemistry column by just adding 18+8 to get 26.

I know this was a little hard to follow along, so here's a picture of it finished:  

b) the dogs need to shift their focus to human scent.

it has changed from the width and the height.

step-by-step explanation: