She cuts off 21 cm. this leaves 63cm. cut into 6 equal pieces gives 10.5 cm pcs
Since the dice are fair and the rolling are independent, each single outcome has probability 1/15. Every time we choose

We have
and
, because the dice are fair.
Now we use the assumption of independence to claim that

Now, we simply have to count in how many ways we can obtain every possible outcome for the sum. Consider the attached table: we can see that we can obtain:
- 2 in a unique way (1+1)
- 3 in two possible ways (1+2, 2+1)
- 4 in three possible ways
- 5 in three possible ways
- 6 in three possible ways
- 7 in two possible ways
- 8 in a unique way
This implies that the probabilities of the outcomes of
are the number of possible ways divided by 15: we can obtain 2 and 8 with probability 1/15, 3 and 7 with probability 2/15, and 4, 5 and 6 with probabilities 3/15=1/5
Combine like terms. The 5x is grouped to the 8x and the -7 isgrouped with the -55.
This means 5x + 8x = 13x and -7 - 55 = -62
The new expression is 13x - 62. We can't find the exact value of x because the expression wasn't set equal to anything.
It would then cost $90 because 25% of $120 is $30
Answer:
D
Step-by-step explanation: