The answer is 180
Step By Step:
1) Set the fraction form of 4.2% equal to 7.56 over a variable
4.2/100=7.56/x
2) Cross multiply
756=4.2x
3) Divide by 4.2 to isolate the variable
756/4.2=4.2x/4.2
x=180
A little hard to read in this format, but I hope it helped!