Question

URGENTE
a- x-y=20
x=4-y

b- x+y=20
x=4y

c- x+y=20
x-y=4

(preciso dos cálculos)

Answer 1

a)

x-y=20

x=4-y

'x-y= 20'

'4-y-y= 20'

4-2y= 20

4-20= 2y

-16=2y

"y= - 8"

x=4-y

x=4-(-8)

x= 12

__________

b-)

x+y=20

x=4y

'x+y= 4'

'4y+y= 20'

'5y= 20'

'y= 20/5'

" y = 4 "

x = 4y = 4.4

"X = 16"

__________

c)

x+y=20

x-y=4(+)

--------------

2x=24

'x=24/2'

"X=12"

'x+2y= 20'

'12+y= 20'

'y= 20-12'

"y=8"