Question

What is 4x+3y=21 5x+2y=21

Answer 1

19x+0=0
19x=0
19x/19=0/19
x=0
Substitute 0 in for x in either equation and solve for y. I'm choosing E2, Why don't you use E1 for fun. You'll find you get the same answer.
5(0)-2y=-14
0-2y=-14
-2y/-2=-14/-2
y=7
The solution is (x,y)=(0,7)

Answer 2

since 4x+3y=21, 3y=21-4x and y= 7-4x/3
subsitute y in to the other equation and we get 5x + 2(7- 4x/3) = 21, which simplifies to 5x + 14 - 8x/3 = 21. it then simplifies to 7x/3 = 7 . multiply both sides by 3 and we get 7x = 21. therefore x is equal to 3
put x in the furst equation again and we get 4(3) +3y =21, this simplifies to 3y = 9 then y = 3
there fore the point (x,y) is (3,3)