This is a simultaneous equation, and you can solve it using the substitution method. You can put the values for y into the first equation.
Therefore: x + (3x - 1) = 19
We can simplify this equation: 4x - 1 = 19
Next, we have to make 4x on its own, and so add 1 to both sides: 4x = 20.
To find x on its own, we have to divide both sides by 4: x = 5
To find the value of y, you can substitute the value of x that we just found out into the second equation: y = 3 x 5 - 1
Simplify: y = 14
Therefore, x = 5, and y = 14