Answer: -4
Step-by-step explanation:
The associative property never works with subtraction.
For example:
2 - (7-8) <span>≠ (2-7) - 8
2-(-1)=3, but (-5)-8=-13
</span>
We calculate the speed by dividing the distance over time:
s = d/t
So the distance described in the problem is always the same, A to B and B to A.
But we are told that;
7 = d/t
7 = 2d/(t + 2)
that is, the first equation say that at speed 7 km/h a distance d is walked in a time t
the second equation say that at a average speed of 7 (that is 8 on one way and 6 in the other: 8 + 6 = 14, half of it), twice the distance is walked in a time equal to the first time plus 2 minutes.
So we have a system of linear equations, 2 of them with two unknowns, we can solve that:
7 = d/t
7 = 2d/(t + 2<span>)
</span>lets simplify them:
7t = d
7(t + 2) = 2d
7t = 2d - 14
we substitute the first in the second:
<span>7t = 2d - 14
</span><span>7t = d
</span>so:
d = 2d - 14
d = 14
so the distance between A and B is 14 km
Answer:
A, B, C
Step-by-step explanation:
The total number of students is the sum of the students taken each course. Hence the total number of students is:
Total number = 6 + 10 + 18 + 4 + 12 = 50 students
A) The percentage of students offering chemistry = (number of students offering chemistry / total number of students) * 100%
percentage of students offering chemistry = (10 / 50) * 100% = 20%
Option A is correct
B) number of students taking health science = 12, while number of students taking physics = 6. Hence About twice as many students are taking Health Science than are taking Physics.
Option B is correct.
C) The percentage of students taking physic = (6 / 50) * 100% = 12%
Therefore for 150 students, the number of students taking Physics = 12% * 150 = 0.12 * 150 = 18
Option C is correct
D) The percentage of students taking earth science = (4 / 50) * 100% = 8%
Therefore for 25 students, the number of students taking earth science = 8% * 25 = 0.08 * 25 = 2
For every 150 students we could predict that 18 of the students are taking Physics.
Option D is correct
Answer:
b. 158cm^2
Step-by-step explanation:
A=(b)(h)
(7)(17)=119
A=1/2(b)(h)
1/2(6)(13)=39
119+39=158
