Is (1,8) solution to the system of equations x+y=9, 2x+2y=18

x  +  y = 9

2x+2y =
18

To check if (1,8) is a solution to this system, just
plug the numbers into the equation

First let's check the
first equation

1 + 8 = 9  add
1 and 8

By adding, you should
get

9 = 9 since this equation
is true we should check the second equation

2
( 1 ) + 2 ( 8 ) = 18  multiply 2 with 1 and 2 with
8

By multiplying, you should
get

2 + 16 = 18 add 2 with
16

By adding, you should
get

18 = 18 this equation is
true also

Since both of the equation were true, that means
(1,8) is a solution to this
set