# Hi can someone help me solve the following using substitution or elimination methos?

( 1) -2.8x-36.6=-7y+4 and 7y=3.2x+46.4-y

(2)3y-5x=7x-64.5 and 10x=11-2y

(3)-17y=2x-56-21y and 9y-x=-63

2) The expression is

---------------> (1)

-------------------> (2)

Multiply equation (1)*2 and equation (2) * 3 and adding

x value substitute equation (1)

edited Apr 12, 2014 by ashokavf

3) The expression is

---------------(1)

----------------(2)

Multiply equation (1)*1 and equation (2) * 2

y value substitute equation (1)

1) First equation is  - 2.8x - 36.6 = - 7y + 4

Second equation 7 = 3.2 + 46.4 - y

Write the equations in slope intercept form y  = mx  + b

Where m  is a slope and b  is y  intercept.

First equation - 2.8x - 36.6 = - 7y + 4

7y = 2.8x + 36.6 + 4

7y = 2.8x + 40.6

y = 2.8x/7 + 40.6/7

y = 0.4x + 5.8

Second equation 7y = 3.2x + 46.4 - y

8y = 3.2x + 46.4

y = 3.2x/8 + 46.4/8

y = 0.4x + 5.8

Observe the two equations are equal .

There are infinity many solutions.