Answer of a ²-10a+16-6b-b^2

$=(a^2-10a)-(b^2+6b) +16$

$=[(a^2-2(5)a+25)-25]-[(b^2+2(3)b+9)-9]+16$

$=(a-5)^2-25-(b+3)^2+9+16$

$=(a-5)^2-(b+3)^2$

i think there was a typo. you wrote pat brings 3 quarts of ice-cream to the party. each serving of ice-cream is 1 6 quart. how many total servings of ice-cream does pat bring to the party? i think the bold is supposed to be 1/6. so 1 quart of ice cream = 6 servings. 6 * 3 = 18.