Use the following algorithm:

Starting with a number x, multiply it by 2.

Add 10 to the result.

Square the result to get your final number y.

First it says that you have to multiply the number x times 2, this will give you 2x as a result. Next you have to build your equation which is 2x=10, when you have an equation like this, you divide the result with the number before x (x=10:2) your result will be x=5. Now you have to square the result (which is x) to get y, when squaring a number you have to multiply it by itself (depending of how many times it's asking to do so when there's a small number at the upper right corner of your number, that's how many times you multiply it) so if you have to square 5, it should be 5*5 which gives you the result of y being 25.