What least number must be subtracted from each of the numbers $$14, 17, 34$$ and $$42$$ so that the remainders may be proportional?
$$ 14-x:17-x=34-x:42-x$$ $$\Rightarrow \cfrac { 14-x }{ 17-x } =\cfrac { 34-x }{ 42-x } $$ $$\Rightarrow (14-x)(42-x)=(34-x)(17-x)$$ $$\Rightarrow { x }^{ 2 }-56x+588={ x }^{ 2 }-51x+578$$ $$\Rightarrow 5x=10$$ $$\Rightarrow x=2$$ |