Answer:
49mg
Step-by-step explanation:
lets consider 6kg as x for a second. First we need to find how many x's are in 42kg. 6kg=1x so to find the correct amount of x's we need to divide 42 by 6. You would get 7. Multiply 7 by the 7mg and yo would get 49. This is what it would look like with working:
6kg=x or 1x
42/6=7
Now we have 7x's
7x7=49
49mg