your answer is going to be 100 and how you do that is you're going to estimate which means you're taking an educated guess and is it 70 closer to zero or 100 70 is only 20 numbers away and how you find that is by subtracting 100 from 70 which equals 20 and how you do that to see if it's up or down is 50 is in your middle okay so it's going to go from 0 to 50 to 100 on a number line 70 is in between 50 and 100 so that means that you'll be going up now if you did 30 instead of 70 in your equation rounding by 10 then it would be in between the zero and the 50 which that means that you're going down