Question

Y=3x 12 y=7x 20 answer?

Answer 1

Given,

y = 3x * 12y = 7x * 20

y = 36xy = 140x

Let us assume that, the equations are

y = 36xy, and y = 140x.

Substitute y = 140x in y = 36xy, and solve for y.

140x = 36xy

y = 140/36

   = 3.88.

Substitute the value y = 3.88 in y = 140x, and solve for x.

3.88 = 140x

x = 3.88/140

   = 0.027.

Therefore, solution of the equation is x = 0.027 and y = 3.88.

Answer 2

considering the equations as y = 3x + 12 and y = 7x + 20

Subtract the equations from each other

y = 3x + 12

y = 7x + 20

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

0 = -4x - 8

x = -2

Substitute x = -2 in the equation y = 3x + 12

y = 3 * - 2 + 12

y = -6 + 12

y = 6

x = -2 and y  =6