Emily has 32 grams of a 25% sugar syrup, but this is just too sweet for her! how much pure water should she add to have a 10% syrup?

By this information, we know: (just so you know, when I will write the equation, the multiplication sign will be ^)

25%+0%=10%
32g    xg   (32+x)g
Now, we create an equation:

(0.25^32)+(0^x)=0.1^(32+x)
8+0=3.2+0.1x
8=3.2+0.1x
4.8=0.1x
48=x
48 gram.