Question

i need it urgent

Answer 1

THE D?

Answer 2

I THOUGHT THE ANSWER WAS A BUT I SAY IT'S D

Answer 3

let A do the job in x days and B do the job in y days
can you form an expression of them working together ?

Answer 4

x+y=25

Answer 5

nopes,
A can do unit amount of work in 1/x days, B in 1/y days,
so, 1.x+1/y=1/25
got this ?

Answer 6

1/x ***

Answer 7

Good one- Hartnn!

Answer 8

so did u ever get the answer

Answer 9

@terenzreignz

Answer 10

hartnn explained it rather thoroughly... DID you get the part that he said? :)

Answer 11

yes i got that part,

Answer 12

Let's use this, \[\Large 25\left(\frac1x\right)+ 25\left(\frac1y\right)= 1\]

Answer 13

And this represents the first statement, where, if you have them work 25 days, they finish the job. Okay?

Answer 14

yes, i got this part

Answer 15

Actually, to make it easier to write, let's have
\[\Large 25x^{-1}+25y^{-1}= 1\]

Answer 16

What about the other one? They spent 15 days working together...
\[\Large 15x^{-1}+ 15y^{-1}\color{red}{...}\]

Answer 17

And then... A proceeds to work alone, for 20 more hours...
\[\Large 15x^{-1}+ 15y^{-1}+ \color{red}{20x^{-1}}...\]

Answer 18

And this also gets the work done:
\[\Large 15x^{-1}+ 15y^{-1}+ 20x^{-1}=1\]

Answer 19

So what we have here is a system of equations:
Solve for \(\large x^{-1}\) and \(\large y^{-1}\)

Answer 20

\[\Large \color{red}{25x^{-1}+ 25y^{-1}= 1}\]\[\Large \color{blue}{35x^{-1}+ 15y^{-1}=1}\]

Answer 21

So... everything okay now? @msingh
This is just a system of linear equations ^_^

Answer 22

okay

Answer 23

Okay, good.

Answer 24

We already did... we already reduced it to that blue/red system I wrote above, it's only a matter of solving it.

Answer 25

okay

Answer 26

i got x = 50 and y = 50

Answer 27

Great ^_^

Answer 28

@hartnn
and
@terenzreignz
thank u so much