Answer: 55.4 mins
Step-by-step explanation:
pragnesh and qazi = 2hrs
pragnesh and roghui = 3hrs
qazi and roghui = 4hrs
this means for every 1 hour they wold paint.
pragnesh and qazi = 
half of the fence
pragnesh and roghui = 
qazi and roghui = 
quarter of the fence
time taken when they all work together
= + +
= 
= 
= 0.9231 × 60(mins)
= 55.4 mins
Factor because if we have
yz=0 then we can assume y and/or z=0
so factor
so the easiest way is to find what 2 numbers add to -6 and multiply to get 9 so
we know that they must be both - because we must have x+x=(-) and x^2=+ so therefor they must be negative
factors of 9=3 and 3 so
-3 and -3
-3+-3=-6 perfect
(z-3)(z-3)=0
set each to zero
z-3=0
add 3
z=3
z=3 is the answer
This is the concept of algebra, to get the slope of the line we need to rewrite the equation in slope intercept form y=mx+c, where m=slope, c=y-intercept.
Therefore re-writing our expression in slope-intercept form we get:
7x-3y=10
-3y=-7x+10
y=7/3x-10/3
The slope=7/3
hence we conclude that the slope of the line perpendicular to this is -3/7
