# The cruise ship

The cruise ship has a speed of 12 km / h at a calm surface. When we sail 45 km along the river and 45 km back, it took us exactly 8 hours. Which (constant) speed of flow of the river?

**Result****Leave us a comment of example and its solution (i.e. if it is still somewhat unclear...):**

**Showing 0 comments:**

**Be the first to comment!**

#### To solve this example are needed these knowledge from mathematics:

## Next similar examples:

- Tourist Jirka

Distance between the points A and B is 13.5 km. Jirka went from point A to point B unknown speed and for an unknown period of time. Back to the point A went slower by 3 km/h which means that went 20 minutes more. How long Jirka took the return journey? - Wind drift

The plane flies at 860 km/h, passing distance 3000 kilometers with the wind and once again against the wind for 6 h 59 min. What is the wind speed? - Two planes

Two planes flying from airports A and B, 420 km distant against each other. Plane from A took off 15 minutes later and flies at an average speed of 40 km/h higher than the plane from B. Determine the average speed of this two aircraft if you know that it - Speed of car

The car went to a city that was 240 km away. If his speed increased by 8 km/h, it would reach the finish one hour earlier. Determine its original speed. - Discriminant

Determine the discriminant of the equation: ? - Theorem prove

We want to prove the sentense: If the natural number n is divisible by six, then n is divisible by three. From what assumption we started? - Quadratic equation

Find the roots of the quadratic equation: 3x^{2}-4x + (-4) = 0. - Square root 2

If the square root of 3m^{2}+22 and -x = 0, and x=7, what is m? - Evaluation of expressions

If a^{2}-3a+1=0, find (i)a^{2}+1/a^{2}(ii) a^{3}+1/a^{3} - Equation

Equation ? has one root x_{1}= 8. Determine the coefficient b and the second root x_{2}. - Roots

Determine the quadratic equation absolute coefficient q, that the equation has a real double root and the root x calculate: ? - Solve equation

solve equation: ? - Equation with abs value

How many solutions has the equation ? in the real numbers? - Variable

Find variable P: PP plus P x P plus P = 160 - Difference AP 4

Calculate the difference of the AP if a1 = 0.5, a2 + a3 = -1.1 - Expressions 3

If k(x+6)= 4x^{2}+ 20, what is k(10)=? - Reciprocal equation 2

Solve this equation: x+5/x-6=4/11