Guys please help me with this question

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

Acoffee shop orders at most $3,500 worth of coffee and tea. the shop needs to make a profit of at least $1,900 on the order. the possible combinations of coffee and tea for this order are given by this system of inequalities, where c = pounds of coffee and t = pounds of tea: 6c + 13t ≤ 3,500 3.50c + 4t ≥ 1,900 which graph's shaded region represents the possible combinations of coffee and tea for this order?

In the sixth grade 13 out of 20 students have a dog if there are 152 sixth grade students how many of them have a dog