7n - 4 = 31
move -4 to the other side
sign changes from -4 to +4
7n-4+4= 31+4
7n= 31+4
7n= 35
divide both sides by 7 to get n by itself
7n/7= 35/7
cross out 7 and 7 , divide by 7 and then becomes 1*1*n= n
n= 35/7
answer:
n= 5
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