Since we know 14, but we don't know the other number, we use a variable. To do that, we look at the problem, then we figure out the unknown. The unknown is: A number. We know 14. Since "Triple" means 3, we can put the exponent 3 by X.
Therefore, the answer is
.
He traveled 2080 miles after 4 hours. He covered 3640 miles in 7 hours with a constant speed, so we can calculate the speed: 3640/7=520 miles/hour. After 4 hours, he traveled 520*4=2080 miles.
Y+1=-1(x-3) is point slope formula
No. 5 or 6 would be, though.