expressions..

giv u a hint...

addition or subtraction of fractions require the common denominator... while products and quotients do not....

also numerator times numerator... denominator times denominator... cancel out common factors of denominator and numerator...

I'll do two, one addition/subtraction and one multiplication/division

addition
1/3 - (-3/4) using Euler's guidance

this is an addition problem (subtraction is addition of a negative) so
1/3 - (-3/4)=1/3 +3/4
because it is addition the denominators must be common. an easy way to determine a common denominator is to use the product or the denominators (in this case 12=3*4

so I want 1/3=a/12 what is a? a=1/3*12=4.
so 1/3=4/12

now I want 3/4=b/12 what is b? b=3/4*12=9
so 3/4=9/12

now I have both fraction in a common denominator
so 1/3+3/4=4/12+9/12
adding numerators
(4+9)/12=13/12
reducing to proper form
13/12=(12+1)/12=12/12+1/12=1 1/12

multiplication (division is the inverse of multiplication---the old invert the divisor and multiply)
-1 1/4 (-2 4/7)
first you want to convert these to improper form
-1 1/4=-(4/4+1/4)=-5/4
-2 4/7=-(14/7+4/7)=-18/7
so
-1 1/4 (-2 4/7) = -5/4(-18/7)
the produce of two negatives is positive so
-5/4(-18/7)=5/4(18/7)
there's a common factor of 2 in the denominator (4) and the numerator (18) ill reduce this now
5/4(18/7)=5/2*9/7
now multiply the numerators and denominators
5/2*9/7=(5*9)/(2*7)=45/14
put in proper form
45/14=(42+3)/14=42/14+3/14=3 3/14

I find addition/subtraction more tedious than multiplication/division.

Rap