No she is not correct she needs to go back to school and learn math
Answer:
Just divide the numbers by 10 and then multiply the quotient by 2. hope this helped
Use the Cosine Rule
q^2 = 20^2 + 30^2 - 2^20*30 cos 15
= 140.89
so q = sqrt 140.89 = 11.9 (answer)