About 4/5 of all orange juice in the world is produced in brazil. about what percent of all the orange juice in the world is produced in brazil?

Think 5 parts of 100. 100/5= 20.

20 x 4= 80 because you used the 5 part now you have to use the numerator.

80% is your answer!

Hope this helps!

So, you can do 0.5 of the job and your friend can do 0.3 of the job (in one hour)
Working together, you should be able to do 0.7 of the job in 1 hour.

So, let's write it this way:

Now solve for x:
1 * 1 / 0.7
1 / 0.7
x = 1.428571428571429
This can be rounded to 1.43 hours if needed 
The job will take 1.43 hours