jonna is 4 years older than her brother. which of the following expressions shows the sum of their ages if b represents jonna's brother's age?

a: 2b + 4
b: b + 4
c: 2(b + 4)
d: 4b

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)

The volume of gas a balloon can hold varies directly as the cube of its radius. imagine a balloon with a radius of 3 inches can hold 81 cubic inches of gas. how many cubic inches of gas must be released to reduce the radius down to 2 inches?

The random variable x represents the number of phone calls an author receives in a day, and it has a poisson distribution with a mean of 8.7 calls. what are the possible values of x