If b = the number of blue bikes, whtoh algebraic expression represents the
phrase below?
the sum of the number of blue bikes and the 9 red bikes
ОА. b+9
B. b•9
ОСІБ – 9
OD. b= 9

A: b + 9

Step-by-step explanation:

If it's the sum of two numbers it is addition, meaning that you add the number of blue bikes(b) to the number of red bikes(9).

it would open into a square depending on the type of envelope i’m not sure about the second part

= 5

step-by-step explanation:

to find the 15th term substitute n = 15 into the nth term formula

= (- 3 × 15 ) + 50 = - 45 + 50 = 5