There are 5 black keys for each 7 white keys. Hence, the ratio stands at 5:7. To determine how many black keys correspond to 49 white keys, we calculate the scaling factor for the ratio: 49 divided by 7 equals 7. Thus, the original ratio is scaled by 7. Therefore, the total number of black keys equals 5 multiplied by this scaling factor, resulting in 35 black keys.
<span>D=20+50t
120=20+50t
50t=100
t=2 hours
The time variable t ranges from t=-(2/5)hr to t=2hr. Given that they have already covered 20 miles.
[-2/5,2]</span>
Answer:
and 
expressed in interval notation.
Step-by-step explanation:
A compound inequality 
has been provided. Our task is to determine the solution for this inequality.
Initially, we will address each inequality independently, followed by merging the findings by combining the overlapping intervals.
By dividing with a negative number, it is necessary to reverse the inequality sign:
Again, dividing by a negative requires flipping the inequality sign:
In combining both intervals, we will arrive at:
Thus, the solution for the inequality provided is and in interval notation.
