You can solve this one by adding their rates, but you have to invert the numbers they give you to find the rate. Rate is measured in something per unit of time, and "per" indicates division. So the rates are: 1/3 of an hour (Sally) and 1/6 of an hour (Steve). So add the rates: 1/3 + 1/6 = 1/2. (1/3 is 2/6, and 2/6 + 1/6 = 3/6). Since their combined rate is 1/2 of a room in one hour, it takes them two hours to paint the room.
This answer makes sense: It takes Sally three hours by herself; with Steve's help, she's faster, but not THAT much faster, because he's pretty slow. You can often spot-check word problem answers like this by giving it a common sense once-over. If we came up with four hours, that would clearly be wrong: it should take her LONGER if she's getting help.
Answer:
D. A(n) = P + (n-1)i*P
Step-by-step explanation:
The formula to calculate the simple interest is:

Replace i by
, then
SI = Pni
where n is the number of years.
So, for n-1 years, the simple interest is:
SI = P(n-1)*i
The Total amount is:
A(n) = P + (n-1)i*P
Keep in mind the the word "percent" translates to "for each 100." 25% can be read as "25 for each 100," which has the fractional representation

and the decimal representation 0.25. All of these representations are just different ways of writing the same value.
Note too that the fraction

can be reduced to

, so what the question is really asking is: 1/4 of what number is 9?
Well, if we know that 1/4 of the number is 9, we can easily find how large the whole number is by finding all 4/4 of it (the <em>whole</em> number)<em /><em />, or 4 x 9, which multiplies out to
36.
The other angel is also equal to x and the sum of all angels need to be 360:
2x+90+26=360
2x=244
X=122
The awnser will be 16 because the beginning if the trail is not the beginning of a mile