Question

4x+5y=3

-7x-6y=-19
To eliminate x we must find the least common multiple of 4 and 7 . What is it?

Answer 1

7 is prime so multiply them
4*7=28
answer is 28

anyway, multiply top by 7 and bottom by 4 to add to get

28x+35y=21
-28x-24y=-76 +
0x+11y=-55

11y=-55
divide by 11
y=-5
sub back
4x+5y=3
4x+5(-5)=3
4x-25=3
add 25
4x=28
divde 4
x=7

(7,-5)