Equation Word Problem - Please help!?

Question

The Randolphs used 12 more gal. of fuel oil in Oct. than in Sept. and twice as much oil in Nov. as in Sept. If they used 132 gal. for the 3 mo, how much was used during each month?

Answer 1

x = # gallons used in September.
Then x+12 = # of gallons used in October
and 2x = # of gallons used in November
So total used was 4x+12 = 132
4x=120
x = 30 = September
x+12 = 42= October
2x = 60 = November

Answer 2

Let S, O, and N represent the oil used in September, October, and November, respectively. Thus,
O = S+12
N = 2S -> S = N/2

Thus, O = (N/2) +12

S+O+N = 132
(N/2) + ((N/2) + 12) + N = 132
2N = 120
N = 60

Then back substitute:
O = (60/2) + 12 = 42
S = 60/2 = 30.

Thus, S = 30, O = 42, and N = 60; the sum is 132, and our original constraints are satisfied.

Answer 3

Ok, seriously I suck at math and this one is easy. take the 12 that you need to add to october away which leaves you with 120, divide that by 4, seeings how November gets 2 parts which gives you 30, so each month starts of with 30, November gets 2 times that which is 60 and October gets the 12 gallons from the beginning which is 42. So September is 30 October is 42 and November is 60. Thanks, that was fun.

Answer 4

Sep = Oct + 12
Nov = 2 * (Sep)
Sep + Oct + Nov = 132

substituting Oct + 12 for Sep in the second equation...
Nov = 2 * (Oct + 12)

Now the equation in terms of Oct
Oct + 12 + Oct + (2 * (Oct + 12)) = 132
Oct + 12 + Oct + (2 * Oct) + 24 = 132
4* (Oct) + 36 = 132
4 * Oct = 96
Oct = 96/4 = 24

Sep = Oct + 12 = 24 + 12 = 36

Nov = 2 * (Sep) = 2 * 36 = 72