Twelve more than one-fifth of a number is 7.

25 or 15

Step-by-step explanation:

The easiest way to do this is by making an equation. But before that, let us look at this in more detail.

"Twelve more than one-fifth of a number is 7."

We can define "more" as added or addition. So let us put that in our equation.

Next, we have "one-fifth", which is

Lastly, we have " a number". Here is the tricky part. We need to input a variable.

Let us put "" right next to one-fifth since it is one-fifth of a number.

Now that we have our equation, we can solve for

Subtract 12 from both sides of the equation. (You don't need to add a positive sign, but it doesn't change anything.)

Multiply both sides by 5

Therefore, the number is 25. To check, just solve as the question says.

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i dont know

step-by-step explanation:

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.