Answer:
369 students have taken a course in either calculus or discrete mathematics
Step-by-step explanation:
I am going to build the Venn's diagram of these values.
I am going to say that:
A is the number of students who have taken a course in calculus.
B is the number of students who have taken a course in discrete mathematics.
We have that:

In which a is the number of students who have taken a course in calculus but not in discrete mathematics and
is the number of students who have taken a course in both calculus and discrete mathematics.
By the same logic, we have that:

188 who have taken courses in both calculus and discrete mathematics.
This means that 
212 who have taken a course in discrete mathematics
This means that 
345 students at a college who have taken a course in calculus
This means that 
How many students have taken a course in either calculus or discrete mathematics

369 students have taken a course in either calculus or discrete mathematics
Answer:
Step-by-step explanation:
In the normal distribution curve, the mean is in the middle and each line to the left and to the right of that mean represent 1- and 1+ the standard deviation. If our mean is 400, then 400 + 50 = 450; 450 + 50 = 500; 500 + 50 = 550. Going from the mean to the left, we subtract the standard deviation and 400 - 50 = 350; 350 - 50 = 300; 300 - 50 = 250. We are interested in the range that falls between 350 and 450 as a percentage. That range represents the two middle sections, each containing 34% of the data. So the total percentage of response times is 68%. We are looking then for 68% of the 144 emergency response times in town. .68(144) = 97.92 or 98 emergencies that have response times of between 350 and 450 seconds.
2x+4x-4=2+4x
2x+4x-4x=2+4
2x=6
x=3
25-x=15-3x-10
3x-x= 15-10-25
2x= -20
x= -10
4x=2x+2x+5x-5x
2x+2x+5x-5x-4x
0 . no solution