Question 1015938
3a-2b=11
5a+7b=39

multiply 1st equation by 5 and second by 3.

15a-10b=55
15a+21b=117

flip signs on first equation and add - 

-15a+10b=-55
15a+21b=117
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31B = 62

B=2

3A-2(2)=11

3A-4=11

3A=15

A=5