The slope of a line is 3 times the slope of the other line and the tangent of the angle between them is 4/13, sum of their slopes is equal to

Let the slopes of the given lines be m and 3 m. if θ is the angle between them then     tan⁡θ=|3m−m|1+(3m)(m)=413⇒ ±2m×13=41+3m2⇒ 6m2±13m+2=0⇒ m=16 or 2 and m=−16 or −2.For m=2, the sum of the slopes is 4m=8