please..anyone help!!

Sally sells seashells by the seashore. In the morning, her sack of shells weighed 70 N. She sold seventy shells and in the evening her sack weighed 7 N. What was the average mass in kg of the shells she sold? The acceleration of gravity is −9.8 m/s2.

C(x)=x^2−20x+111 represents the total cost, in dollars, to produce x gallons of paint. How many gallons of paint should be produced to minimize the total cost?

How many integers appear in both of the following arithmetic progressions: A1: 2, 9, 16,.....2+(1000-1)*7 A2: 3, 12, 21,.....3+(1000-1)*9 Since 2 appears in A1 but not in A2, it does not appear in both of the arithmetic progressions.

In triangle ABC, ∠ABC=30∘,∠ACB=60∘. D is a point in triangle ABC such that DB and DC bisect angles ABC and ACB respectively. What is the measure (in degrees) of ∠BDC?