One student can paint a wall in 10 minutes. another student can paint the same wall in 15 min. working together, how long will it take for them to paint the wall

6 minutes

Step-by-step explanation:

Formula

1/15 + 1/10 = 1 / x where x is the time it takes both of them to do the job.

Solution

The lowest common denominator for 1/15 and 1/10 is 30

2/30 + 3/30 = 1/x

5/30 = 1/x              Cross multiply

5x = 30                  Divide by 5

5x / 5 = 30/5

x = 6

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

0.6

39mph

step-by-step explanation: