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50 g of liquid X at 10 Celcius and 200 g of liquid Y
mx*cx*(t-tx)+my*cy*(t-ty)=0
cx/cy = - my*(t-ty) : mx*(t-tx) = (my/mx) * (ty - t) / (t-tx)
cx/cy = 200/50*(40-15)/(15-10) = 20
cx/cy = 20
True, the accepted modern theory of life is biological evolution.
In a distance time graph, when the x and y values are positive (in first quadrant), the runner is moving forward.
While, if the distance value ( in the y axis) is negative, the runner is moving backwards ( towards the start) .
Hope it helps :)