its 14n+21. 7×2n is 14n, and 3×7 is 21
Answer:
1.4x 2 +7x−9
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Answer:
YZ = 1
XY = 1.5
XYZ 1.33
Step-by-step explanation:
Given:
Either has a school certificate or diploma or even both = 20 people
Having school certificates = 14
Having diplomas = 11
To find:
The number of people who have a school certificate only.
Solution:
Let A be the set of people who have school certificates and B be the set of people who have diplomas.
According to the given information, we have
We know that,
Subtract both sides by 25.
We need to find the number of people who have a school certificate only, i.e. 
.
Therefore, 9 people have a school certificate only.
Roberto overtakes Juanita at the rate of (7.7 mi)/(11 h) = 0.7 mi/h. This is the difference in their speeds. The sum of their speeds is (7.7 mi)/1 h) = 7.7 mi/h.
Roberto walks at the rate (7.7 + 0.7)/2 = 4.2 mi/h.
Juanita walks at the rate 4.2 - 0.7 = 3.5 mi/h.
_____
In a "sum and diference" problem, one solution is half the total of the sum and difference. If we let R and J be the respective speeds of Roberto and Juanita, we have
R + J = total speed
R - J = difference speed
Adding these two equations, we have
2R = (total speed + difference speed)
R = (total speed + difference speed)2 . . . . . as computed above
