help needed!!!

Rewrite
5x+ 40 = 64xy
x - 20 = 10xy

Eliminate xy by finding LCM of 64and 10, multiplying each equation by LCM and subtracting. Hence solve for x then for y.

Re: help needed!!!


Lets simply add the two equations:

7x = 84xy

Assuming x is not zero (looking at the original equations, there is clearly no solution with x = 0), we can obtain the solution by dividing this equation by x:

7 = 84y

y = 1/12

Substituting this result back into 5x + 40 = 64xy, we obtain:

5x + 40 = (5 1/3) x

40 = (1/3)x

x = 120

Thank you fresco and Brandon9000, you both were very helpful.

Gerd,

Sorry, LCM doesnt come into it ! (Alzheimers ? )

Multply first equation by 10 and second by 64 giving

50x + 400 = 64x - 1280

Whence x = 120

substituting

120 - 20 = 1200y
y = 1/12

which agrees with Brandon.