Answer:
6
Step-by-step explanation:
because you divided the amount of mile by the amount of time it took to get your answer
Use a number line if you need 4/10 - 6/10 = -2/10a simpler way is to do the opposite 6/10 - 4/10 = 2/10 then the answer would be the opposite as well. so, -2/10
Parallel lines have equal slopes