I think it’s 9.10 but I’m not really sure
28 each book 155-15=140 and then 140÷5=28
Answer:
D is the answer.
Step-by-step explanation:
You can see if a line is perpendicular by the slope. If the slope is COMPLETELY opposite from another by means of slope, the lines are perpendicular.
-1/4
4/1
...are opposite.
Since y is less than x by 7 times

so in terms of x we write
x=7y