Idon't get it. the part is the answer and what to do

 The answer is:   f < 140  .
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Explanation:
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Given: 
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 →    − 22 <  48 ;
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 → We add "22" to EACH side of the "inequality";
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           →    − 22 + 22 <  48 + 22 ; to get: 

                        →     <  70 ;  

Now, we multiply EACH side of the inequality by "2" ; to isolate "f" on one side of the inequality; and simplify ;
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                        →   { } *2 < 70* 2 ;

                                  → to get:  f < 140  ; which is our answer. 
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