Work with a friend and without a calculator. Calculate the answers to the following questions.

a. 38 + 12 

b. 45 + 25 

c. 66 + 34 

d. 23 + 27 

e. 59 + 31 

f. 34 − 12 

g. 45 − 34 

h. 98 − 65 

i. 54 − 48

j. 81 − 55