First you have to calculate the volume of the box V=a * b * c if it is a= 3m= 300cm, b=1m 68cm = 168cm and c= 120cm, then V= 300cm * 168cm * 120cm = 6.048.000cm^3
Now you have to calculate the volume of the soap bars V1= a1 * b1 * c1 if it is a1=12cm, b1=8cm and c1=7cm
V1= 12 * 8 * 7 = 672 cm^3
When you divide V and V1 you will get the required number