Answer:
OR 5g : 8g
Step-by-step explanation:
Also a ratio can also be represented by a fraction; 
So to make the ratio to the simplest form we have to divide by a number that can divide both number.
40g : 64g
We can start dividing by 2 which will give us;
20g : 32g

Now we can divide by 2 again since it can divide both numbers which will give us;
10g : 16g

We can still divide by 2 since it can divide both numbers which will give us;
5g : 8g

Since no numbers can divide 5 and 8 equally that is our answer.
Also, 
Where are the two questions ?
If you notice the terms, they're
7, -21, 63, -189 and so forth.
7*-3 = -21 and -21 * -3 is 63 and so forth, meaning the "common ratio" is -3.
now, for a common ratio say "r", which is a fraction, namely less than ±1 and more than 0, or |r| < 1 , you do have a convergent sequence.
however this one notice, |-3| is 3, and that's greater than 1 clearly, therefore is divergent, meaning the summation has no finite value.
Nine hundred thirteenths if this is a decimal