If the denominator of two fractions are both the same just add or subtract the numerator , it depends on the sign .. however if its not the same, get the product of denominator and cross multiply through opposite numerator and denominator simultaneously combined the solve product of numerator. and get the lowest term of the denominator and numerator after you combined..

mixed no.   
let c= quotient
     r= remainder
     d= divisor 
c r/d  which means if u divide a number by the divisor and if it contains a remainder , then put it in the formula ..
example:  5      divide it by 3
           quotient is 1 remainder is 2
    c r/d          mixed fraction is 1 2/3

checking:    multiply the divisor into quotient and add the numerator.. ans=5
Just simply add the numerator if the denominators are the same but if the denominators are not the same find the GCF (Greatest Common Factor) of it then multiply it by the numerator then you have the answer.

multiply the denominator and the whole number then add the product and the numerator..

hope it helped you :)