is (4,-18) a solution of 4x+5y=1?

Is
4(4)+5(-18)=1 ?

Check
16 - 90 = - 74

Not a solution.

Substituting with x = 4 and y = -18 in the equation i we get resultant equal to 1 , then we can say( 4 , -18 ) is a solution , not otherwise,
4 ( 4 ) + 5 ( -18 ) = 16- 90 = -74 , so -74 is not equal to 1 and therefore ( 4 , -18 ) is not a solution of 4x +5y = 1

When x = 4 and y = -18 :

L.H.S.
= 4(4) + 5(-18)
= -74

R.H.S. = 1

L.H.S. ≠ R.H.S.
Thus, (4, -18) is NOT a solution of 4x + 5y = 1

No

4(4) +5(-18) = 16 - 90 = -74

It does not equal 1

(4,-3) is a solution