The potential energy is 784 J when it's sitting on the stop of the building.
Step-by-step explanation:
length can be find out by using the formula

now put values




similarly




and finally



i hope u will understand
You can do 10-8=2 and then 2+5=7 which is the same as 15-8
So after 100 its 105,112,119...........994
x=7(multiples of what we're finding), y=105(where we start from after 100), a multiplied by z=994
we have to find z
994=105+(z-1)7
994-105=7z-7
889+7=7z
896=7z
z= 128
Answer: 
<u>Divide</u>
30÷75%=40
<u>Final Answer</u>
40
Note: When finding answers like these divide the number by the percent.