Answer:
Tommy Thomas's tankard holds 160ml when it is one-quarter full.
Step-by-step explanation:
When Tommy's tankard holds 480ml when it's one-quarter empty. There are three other quarters in the tankard. So, you would divide 480 by 3 to see how much is in each of the other 3 quarters. The answer comes down to 160ml per quarter, which equals one-quarter full.
Looks like you just evaluated the summand for the given value of

, whereas the question is asking you to find the value of the sum for the first

terms.
Let

. Then

is the

th partial sum.

happens to be the first term in the series, which is why that box is marked correct:

But the next partial sum is not correct:

and this is not the same notion as the second term (which indeed is 0.75) in the series.
Well...
2x-6x>-12+8-6
-4x>-10
Attention! ">" change for "<" because we multiply both members for (-1)
x<10/4
It is the same to say (-infinite ; 10/4) or (-infinite ; 5/2) or (-infinite ; 2.5)
Good luck!
M.