What is x if x + 3y = 10 and y = 3?  Choose the correct choice from the following options
A) 1 B) 2 C) 3 D) 4 E) 5

Rationale: "substitute y by 3 in x + 3 y = 10 x + 3 ( 3 ) = 10 x + 9 = 10 if we substitute x by 1 in x + 9 = 10 , we have 1 + 9 = 10 . hence x = 1 correct answer a"
Answer: A