If they are not on the same dimension then you cannot do this. They will be different numbers and will not go together.
No, it is not.
Yes they must be in the same units of measurements.
Yes.
When adding or subtracting fractions their denominators must be the same
If they are not on the same dimension then you cannot do this. They will be different numbers and will not go together.
Efficiency is a ratio of the same quantities. Usually, output power / input power. As the numerator and denominator have the same quantities, the dimensions cancel each other out.
No, it is not.
Yes they must be in the same units of measurements.
No
Yes.
When adding or subtracting fractions their denominators must be the same
It is called algebra. When two quantities are related as long as you do the same operation to both (add, subtract, multiply, or divide) you do not change the relation
Same direction and equal magnitudes.
No, it is not true.
If you intend 'dimensions' to mean units then whenever the two quantities are to be operated on each other then they must have the 'dimensions', refer to dimensional analysis
dimensional consistency says that in any equation the dimensions of the quantities in the rhs and lhs are same. for example force =mass*acceleration force dimensions are MLT-2 : mass dimension M ;acceleration dimension LT-2 togehter the right hand side is also having MLT-2 dimension same as that of force.