Put it into a proportion... x/125 = 35/100, multiply cross parts, (125)(35)=100x, then distribute, 4375=100x. Lastly, divide, 4375/100 = 43.75.
43.75 is the answer.
A quicker way, because any decimal point is out of one hundred, 35/100 is the same as .35, so .35x125=43.75