" "ALLOY”" "

In two alloys the rations of copper to tin are 3:4 and 1:6 respectively. If 7 kg. of the first alloy and 21 kg. of the second alloy are mixed together to form a new alloy, then the ratio of copper to tin in the new alloy is :

There are two alloys made up of copper and aluminum. In the first alloy copper is half as much as aluminum and in the second alloy copper is thrice as much as aluminum. How many times the second alloy must be mixed with first alloy to get the new alloy in which copper is twice as much as aluminum?