Question 637278
"=>" means implies
3(x) + 7 = 4

# subtract 7 from both sides of the equation
=> 3(x) + 7 - 7 = 4 - 7  # by equality property a = b => a+c = b+c
=> 3(x) + 0 = -3
=> 3(x) = -3
=> x = -3/3
=> x = -1 is  the solution