B. Because the divisor, 4.2, has only value in the ones and tenths places, so we only have to multiply by 10 to get to 42, which is the whole number you need.
For f(3)...put 3 as the value of x in f(x)
for x.....put the value of f(x) from the given and equate it with 14..and solve
B is the answer
just like the picture
( T' is not exact. it just shows the reflection)
✧・゚: *✧・゚:* Hello ✧・゚: *✧・゚:*
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I will give you a explanation about how I got the answer!
Plus, I'm am so sorry if I answer this so long...
Hope It Helped! :)