I need help with math! I don't understand it. Can someone show me step by step.

7) refer to d=rt triangle so answer is t= d/r

8) rearrange by dividing so it should be PV/nR = T

9) move 5r to  other side which become 2p = q - 5r then divide by 2. final answer is p = q-5r/2

10) multiply both side by b/1 so b got cancel on left side

right side become c(b/1) which is same as cb

then you divide both side by c to isolate b on the right side

final answer is a/c=b

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.