What are you trying to find out the length of
To solve this we are going to use a conversion factor. We know that 1 BTU per hour is approximately 778 foot-pounds of energy per hour, so our conversion factor will be:

.
Now we just need to multiply <span>4000 BTU by our conversion factor:
</span>

<span>
We can conclude that the furnace released </span><span>
3,112,000 foot pounds of energy in one hour.</span>
<span>let the angles be x and y.
as they are compliment
x+y=90
also given
x=7y
substituting value of x in first equation
7y+y=90
8y=90
therefore
y=11.25
x=7*y=78.75</span>