Exercise $-$ Lever rule

$=>\frac{b-\text{m}\text{a}\text{d}-aL}{b}$

A mixture of $A30\%+B70\%$ is cooled from $1400C$ to cross the liquidous line, where we see crystal B start to form. When the mixture is cooled further to the temperature of the red line, how much Crystal B forms from $100kg$ of the mixture? What's the composition of the melt at the temperature?