Solve for Y.

3Y + 8X + 3 = 19 + 8X

Subtract 3

3Y + 8X + 3 - 3 = 19 - 3 + 8X

3Y + 8X + 0 = 6 + 8X

3Y + 8X = 6 + 8X

Subtract 8X

3Y + 8X - 8X = 6 + 8X - 8X

3Y + 0X = 6 + 0X

3Y = 6

Divide by 3

3Y/3 = 6/3

Y(3/3) = 6/3

Y(1) = 2

Y = 2

Done.

Y-intercept is the constant term, 2

Slope is the coefficient on X, 0

What are you not seeing?