Question

solving by addition: find X and Y
2x+3y=7-2x
7x+2y=9

Answer 1

2x+3y=7-2x
4x+3y=7

Answer 2

7x+2y=9
4x+3y=7

Answer 3

x = 1, y = 1

Answer 4

starting with the second system by Libniz, you could multi. the first equation by 3, and the second equation by -2; that way the y coefficients will be opposites and will be eliminated when the two equations are added together:

21x+6y=27
-8x-6y=-14
========
13x =13
x=1

now back sub to get y; i'll choose the original second equation (you know that you can use any equation that has a y in it)

7(1)+2y=9 (sub in 1 for x)
2y=9-7 (subtract 7 from both sides)
y=1 (divide through by 2)

the answer may be written as x=1, y=1; some like it as (1,1)