The sum of twice a number and 5 is 21. What is the number?

Hello.

First, "twice a number" means we multiply 2 times that number.

Let the number be s.

Now, the sum of 2 times s and 5 is 21.

The product of 2 and s can be written like so:

Now, the sum of 2s and 5 is 21:

Subtract 5 from both sides:

Now, divide both sides by 2:

I hope it helps.

Have a nice day.

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step-by-step explanation: