Okay kiddo, so you remember how we add numbers together like 2 + 3 = 5, right? Well, sometimes we aren't just adding regular numbers, we're adding things like how much a plant grows each day or how fast a car is going at any moment. These things can change over time, so we need a special kind of math called calculus to help us solve them.
In calculus, we use something called a differential equation to describe how these things are changing. It's like a math sentence that tells us how one thing affects another thing. For example, if we want to know how fast a car is going, we can use a differential equation that tells us how its speed is changing over time.
Now, let's say we have two different things that are changing over time, like the growth of two different plants. We can use two different differential equations to describe how they are growing, and then combine them using addition. This gives us a new differential equation that describes the combined growth of both plants.
It's like if we have two toys - a ball and a teddy bear - and we want to play with them together. We can put them both in a toy box and then take them out and play with them as one big toy. Similarly, we use differential equations of addition to combine the changes of different things together and describe how they affect each other.