Which is the following is a run on sentence

Liam's parents are driving three times as fast as liam is biking, but they left later than he did. if his parents caught up with him two hours after he left, how much later than liam did they leave?

Average acceleration: i have no idea how to do this.

Which equation is true? i. 56 ÷ 4·7 = 82 ÷ (11 + 5) ii. (24 ÷ 8 + 2)3 = (42 + 9)2 neither i nor ii ii only i and ii i only