The bar between the numerator and denominator of a fraction represent division.
1: not sure what you mean
2: to add and subtract, get common denominator. To multiply, multiply the terms horizontally. To divide, multiply by the reciprocal
3: multiply by reciprocal. Multiply the number part and fraction part.
4: volume=length*width*height
5: count all the cubes inside
60. set up ratios 45/75 = x/100