Manipal Entrance Test 2015 Math Paper

There are 6 letters in the word ‘DEGREE’, namely 3E's and D, G, R. Four letters out of six can be selected in the following ways:
(i) 3 like letters and 1 different, viz. EEE + D, G, R
(ii) 2 like letters and 2 different, viz. EEE + any two of D, G, R
(ili) All different letters, viz. EDGR
So, the total number of ways =‌3C1+‌3C2+1 =3+3+1=7