What would you have to get to have 7 times 12 times blank equal 28,000
2 answers:
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We have that F is proportional to m1. Hence, we have that F=m1*c when we change the first mass. We also have that F=m2*c when we only change the 2nd mass. Since F scales inversely with the square of the distance, we have that 
. Combining all of the facts above, we get that F=c*
where c is a constant.