90% out of 105% which would be 0.85
remember that
![x^{\frac{a}{b}}=\sqrt[b]{x^a}](https://tex.z-dn.net/?f=x%5E%7B%5Cfrac%7Ba%7D%7Bb%7D%7D%3D%5Csqrt%5Bb%5D%7Bx%5Ea%7D)
also 
and 
so

first one, that one is clearly not equal since 0.25≠4
2nd one, 0.25=1/4, so
, which matches
3rd one,
, which matches
4th one
which matches
answer is 
Abcdefghijklmnopqrstuvwxyz
1) move the 10 over
So it becomes
3/4b = 10
2) multiply everything by 4 to get rid of the denominator
2b = 40
3) divide both sides by 2
b = 20