Density= mass/volume,
The answer to this mathimatical equaion is N (+1+1x2) so u multiply N times postive 1 then add N times postive the N times 2 so it ends up N(1)+N(1)+N(2) then it is N1+N1+N2=N4
300 Find the difference (500-100=400) then halve the sum(200). Add the halved sum to the lowest number in the equaion(100) or subtract the halved sum(200)from the largest number in the equation(500) one:500-100=400 two:400/2=200 Three: 200+100=300 or 500-200=300