Easy! multiply the 6% by $8 then add it to the $8, now, multiply the 15% by the total of the cost with tax. then you all that to the total. ($9.75)
Seeing you don't have a graphing calculator, use the web, there are many websites dedicated to different calculators
The answer is 1/4.
The genes when combined must be Heterozygous, meaning they have one dominant and one recessive, Celia must have gotten the 1/4 recessive, and it won't change the way genetics are just because you've already had offspring, the percentage stays the same.
