I know u are supposed to use formulas to do this...but it is just as easy to do it this way...that is, if u dont have many numbers...if u were looking for s20, we would have used formulas...lol
u will notice that in ur pattern, their is a difference of 5 between each number....this is an arithmetic sequence
start at 3
3 + 5 = 8
8 + 5 = 13
13 + 5 = 18
18 + 5 = 23
23 + 5 = 28
28 + 5 = 33
thats ur first 7 numbers...so just add them and u will have s7
s7 = 126
first car is x
second car is y
25x+30y=1550
x+y=55
Multiply the second equation by -25 for elimination method to cancel out x
-25x-25y=-1375
Add the two equations
5y=175
y=35
Plug this value into the second equation
x+35=55
x=20
Final answers:
First car=20 gallons
Second car=35 gallons
