Answer:
Train A - 50 miles per hour
train B - 30 miles per hour
Step-by-step explanation:
Let x mph be the speed of the train B, then the speed of the train A is (x+20) mph.
In 3 hours,
- train A travels 3(x+20) miles
- train B travels 3x miles
In total, they covered the distance of 240 miles, so
![3(x+20)+3x=240\ \ \ \text{[Divide by 3]}\\ \\x+20+x=80\\ \\2x=80-20\\ \\2x=60\\ \\x=30\ mph\\ \\x+20=30+20=50\ mph](https://tex.z-dn.net/?f=3%28x%2B20%29%2B3x%3D240%5C%20%5C%20%5C%20%5Ctext%7B%5BDivide%20by%203%5D%7D%5C%5C%20%5C%5Cx%2B20%2Bx%3D80%5C%5C%20%5C%5C2x%3D80-20%5C%5C%20%5C%5C2x%3D60%5C%5C%20%5C%5Cx%3D30%5C%20mph%5C%5C%20%5C%5Cx%2B20%3D30%2B20%3D50%5C%20mph)
Line up the decimal point to each number in order from left to right and subtract to get the difference which should be -0.248
The concept of the question above is Permutation where in we are to arrange to arrange the 6 students from which there are 20 students. This is the "permutation of 20 taken 6" or 20P6. The numerical value of the permutation is equal to 27907200.
Step-by-step answer:
Given:
Initial monthly salary = $5000
New salary = 10% less
Salary a year after = 15% more
Solution:
New salary
= 5000 * (100-10)%
= 5000 * 90%
= 5000 * 90/100
= 4500
Salary a year after
= 4500 * (100+15%)
= 4500 * 115%
= 4500 * 115/100
= 45*115
= 5175
