Question

if 3x=5y and x+y=80,then y=​

Answer 1

Answer:

hello mate

_________

3x = 5y

or

3x - 5y = 0 --------(1)

x + y = 80

we multiply =n 2 by 3

thus

3x + 3y = 240-------(2)

subtracting equation 2 from 1 , we get3x - 3x - 5y = 0

3x + 3y = 240

-__________

• 0x -2y = -240

• -2y = -240

• 2y = 240

• y = 240/2

• y = 120

ANSWER ;-

Y = 120

thanks :)

________

Answer 2

if 3x=5y

than x=5y/3 .........(i)

x+y=80..........(ii)

put the value of equation (i) on (ii)

$\frac{5y}{3} + y = 80$

$\frac{5y + 3y}{3} = 80$

$5y + 3y = 240$

$8y = 240$

$y = \frac{240}{8}$

$y = 30$

$put \: the \: value \: of \: y \: on \: equation \: (i)or \: (ii)$

$x + y = 80$

from ii

$x + 30 = 80$

$x = 80 - 30$

$x = 50$

hope this will help you

this is substitution method