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
Subtract the numbers
Factor out 4 from the expression
When there is a - in front of an expression in parentheses, change the sign of each term in the expression to -
let's think about it, let's divide say hmmm 15 by 0, in a fraction
now, how can you take any pieces of a pie that's non-existent? I mean that requires magic!!.
now, let's do it using a simple long division, 15 ÷ 0, so 0 is the divisor, anything times 0 is 0, what is our first digit in the quotient to get 15? 0 * 15 = 0, 0 * 1,000,000 = 0, there isn't any number we can possible use to get a quotient.