To find the Gear ratio of the Driving gear, 40 teeth; driven gear, 5 teeth.

Concept used:
Gear ratios are generally, given as some quantity to 1. If we divide both term of the ratio by the second term, we will get the ratio of some number to 1.
Formula used:
Gear ratio ${\displaystyle =\frac{\text{ratio of driving gear}}{\text{ratio of driven gear}}}$
Calculation:
Putting the given values in the above formula, we get
Gear ratio ${\displaystyle =\frac{\text{ratio of driving gear}}{\text{ratio of driven gear}}}$
Calculation:
${\displaystyle =\frac{40}{5}=8}$
The gear ratio is 8. Gear ratios are generally given by some quantities to 1. If we divide both the terms of the ratio by the second term, we will obtain a ratio of some number to 1. Dividing both 40 and 5 gives the gear ratio of ${\displaystyle 8:1}$
Conclusion: The gear ratio of ${\displaystyle 8:1}$.

Answer is given below (on video)