Let's first break it down to the time 8 people need for one wall. That would be 10 minutes, right? If one person would have to do it in stead of 8, you'd expect him to take 80 minutes.
To paint 7 walls, he would nee 7x80 = 560 minutes. 10 people would do that 10 times faster, ie., 56 minutes.
I know puzzles like these always have a mindtrick. Did I miss anything?? ;-)
Answer:
27 and 40
Step-by-step explanation:
A) -6a = 36
Divide both sides by -6 so that (a) is isolated.
a = -6
Check by plugging in -6 for a.
-6a=36
-6(-6)=36
36=36
So, a=-6
B) -9d=-72
Divide both sides by -9.
d = -72/-9
d = 8
Check work by plugging in 8 for d.
-9d=-72
-9(8)=-72
-72=-72
So, d=8
~Hope I helped!~
