A tank initially contains 84 liters of milk and 112 liters of orange juice. If (6a-3) liters of milk and 3�−2" id="MathJax-Element-133-Frame" role="presentation" style="position: relative;" tabindex="0">3�−23�−2" id="MathJax-Element-173-Frame" role="presentation" style="position: relative;" tabindex="0">[Math Processing Error]3�−2" id="MathJax-Element-3-Frame" role="presentation" style="position: relative;" tabindex="0">3�−2$3�-2$ $3�-2$ $3�-2$ $3�-2$ (7a+4) liters of orange juice are added to the tank, the ratio between milk and juice remains the same. Find the value of 'a'.