You just divide both sides by 7:
7k/7 = 77/7
k = 77/7
k = 11
Final answer: k = 11
There you go the answer key
First you need to know the prime numbers from 1-10.
They are 2, 3, 5, 7,
1st draw: P(prime) = 4/10
2nd draw: P(prime) = 3/9
Multiply these numbers 12/90 = 2/15
rate of blowing balloons of Alexa = 15/20 = 0.75
rate of blowing balloons of Sara = 18/25 = 0.72
rate of blowing balloons of Shirley= 16/21 = 0.76
rate of blowing balloons of Sam = 12/23 = 0.52
from above calculation we concluded Shirley can blow balloons at the fastest rate!
Yes 2,1 is a solution of this problem