X=time of the third person it would take to fill the pool
We can suggest this equation:
6[(1/20) + (1/15) +(1/x)]=1
6[(3x+4x+60)/60x]=1
(7x+60)/10x=1
7x+60=10x
7x-10x=-60
-3x=-60
x=-60/-3
x=20
Answer: the third person alone would fill the pool in 20 hours .
1st one: zero
2nd one: one
Answer:
This shape is a rectangle so that means that the angles are 90°. From sum of angles of a triangle, x + 3x + 10 + 90 = 180 which means 4x + 100 = 180 → 4x = 80 → x = 20°.
