Answer:

Step-by-step explanation:
The systems of equations are
Let us assume the rate of the current be c
Now actual speed against the current is (15 - c)
And, the actual speed with the current is (15 + c)
Here we applied the time formula i.e. distance by speed
Also the upstream time - downstream time = 4
Now the equations are

Answer: 3/20 of the class
Step-by-step explanation:
Add the amount of students that play soccer to amount of students that play volleyball
1/4 + 3/5 = 17/20
Subtract 17/20 (soccer and volley ball) from 20/20 or 1
20/20 - 17/20 = 3/20
B (2+x) +3y
Other examples include <span>(14 + 6) + 7 = 14 + (6 + 7)
because </span><span>Adding 14 + 6 easily gives the sum of 20 to which we can add 7. The right hand side of the equation is where we add 14 and 13. Both sides will result in 27.</span>
When adding/subtracting fractions you need a common denominator, but you already have one, which is x-3. So in general:
a/c-b/c=(a-b)/c so you just have:
(2x-6)/(x-3) now if you factor 2 from the numerator
2(x-3)/(x-3) the (x-3)s cancel out leaving
2
However! Note that division by zero is undefined, so x cannot equal 3. (because both original fractions had denominators of x-3)
What this all means is that that expression will equal 2 for all real values of x other than 3.