What is the value of x in the equation 1/5x – 2/3y = 30, when y = 15?

x = 200

Step-by-step explanation:

1/5x - 2/3y = 30

Put y as 15 and evaluate.

1/5x - 2/3(15) = 30

1/5x - 30/3 = 30

1/5x - 10 = 30

Add 10 on both sides.

1/5x = 40

Multiply both sides by 5.

x = 200

The speed of the current is 4 miles/hour

Step-by-step explanation:

Let us assume that,

x = speed of the boat,

y = speed of the current.

We know that,

A motorboat can go 8 miles downstream on a river in 20 minutes or hours.

   --------------------------1

It takes 30 minutes for the boat to go upstream the same 8 miles.

   ----------------------------2

Subtracting equation 1 and 2,

miles/hour