9/19 = x / 152....9 oz oil to 19 gallons gas = x oz oil to 152 gallons gas
cross multiply because this is a proportion
(19)(x) = (152)(9)
19x = 1368
x = 1368/19
x = 72 oz of oil <==
Step-by-step explanation:
5/8 x 3/11 = answer
Keep change flip
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.
