How to write a linear equation with multiple variables?

Question

Java

Good
Long ago, I gnawed the granite of science and now I can’t make a linear equation in any way. The task is this:
“Let there be 3 engine design options. The engine is designed and by increasing the mass of the first engine by 1 kg, its power will increase by 5 horses, the second by 40, the third by 80 (i.e. increase the size of the engine, it becomes heavier and more powerful , the ratio of horses to mass is chosen by the user.) It is necessary to create a car with these engines, where the total power is 2000 horses (or another number, set by the user) and at the same time there is a restriction in the ratio of the mass of engines, i.e. the maximum mass of all three is any, but out of the total mass, the mass of the first engine is 20%, the second 50%, the third 30%
.
1) Find the mass of each engine that satisfies the conditions for the ratio of mass and total power.
2) The mass of each motor if their number is N
Thanks in advance

Answer 1

You have one unknown - the total mass of all engines -
Х. 0.5*X = 2000, solve this equation for X