The bus covered 40% of the journey in the first hour, there are still 90 km left. How long is the entire planned path?

The sought unknown length of the entire planned route will be denoted by the conditional variable “X”.
At the second stage, based on the conditions of the problem, we form the following proportion: 100% relate to X kilometers in the same way as 60% relate to 90 kilometers.
The next step, based on this proportion, is the equation: X x 60 = 100 x 90.
As a result of solving this equation, we get X = 100 x 90/60 = 100 x 1.5 = 150 kilometers.
Answer: the entire planned route is 150 kilometers.