Answer:
1/2
Step-by-step explanation:
Substitute 1/2 as h you get 16*(1/2) you get 4 and -8*1/2 you get -4 so 4+ -4 = 0
Since if he gets the driveway done in 20 minutes he gets 1/20th of the driveway done in 1 minute (if x=20 then x/20=1 by dividing both sides by 20) and if his brother gets 1/12th of the driveway done in one minute, then if t represents the time it takes to shovel the driveway, t/20+t/12=1 driveway shoveled as 1/20+1/12=amount they can do in 1 minute, so t/20+t/12 is how much they can do in t minutes. Multiplying both sides by 20*12=240, we get 12t+20t=32t=240. Dividing both sides by 32, we get 240/32=7.5 minutes to shovel the driveway.
The answer is B: 6 cm. You can use guess-and-check method, and plug the possible different answers into the equation x(x+6)=72, x stands for the width.
