S = n(a1 + an)/2
2S = n(a1 + an)
2S = na1 + nan
nan = 2S - na1
an = (2S - n a1)/n
A + b = 45
a - b = 21
a = 21 + b
Use substitution
21 + b + b = 45
2b = 24
b = 12
45 - 12 = 33
The numbers are 33 and 12
41-28=13 questions, but you also have to do 41 and 28, so 15 questions
Answer:
A = ± 
Step-by-step explanation:
Given
b²A² - 3g = q ( add 3g to both sides )
b²A² = q + 3g ( divide both sides by b² )
A² =
( take the square root of both sides )
A = ± 