Question

is (2,3) a soluition of the system 3x+4y=18 2x-y=1

Answer 1

Yes, it is ;)

Answer 2

Sobstitute x with 2 in first(or second) equation and y with 3 in the same equation, if it's an equivalence then it's true ;)

Answer 3

yes,
(2) 3x+4y=18
(3) 2x-y=1

6x+8y=36
-6x-3y=3
=8y=36
+-3y=3
y=3

2x-(3)=1
2x=4
x=2

Answer 4

THANK YOU BOTH I JUST HAVE TO PLUF IN THE Y AND X =)