Element in group 1 become more stable by

3.5x = 25 + 3x

Step-by-step explanation:

Let x be the speed in miles per hour of both red car and blue car,

We know that,

Distance = speed × time,

If time taken by red car = 3 hours,

Then the distance travelled by red car = 3x

Now, if the time taken by blue car = 3.5 hours,

Then the distance travelled by blue car = 3.5x

According to the question,

Distance covered by blue car = 25 miles + Distance travelled by red car

3.5x = 25 + 3x

Which is the required equation.