At the beginning of the school year dance, the ratio of the number of boys to the number of girls was 3: 7 , if there were 100 more girls than boys, how many boys were at the dance? …. how many girls were at the dance?

boys (b): b

girls (g): b + 100

total (T) = b + g

I am going to set up the proportion as "boys" to "total"

⇒

⇒ 3(2b + 100) = 10(b)

⇒ 6b + 300 = 10b

⇒          300 = 4b

⇒            75 = b

girls (g): b + 100   = (75) + 100   = 175

boys = 75, girls = 175

an = 22 + (n-1) *6

110 seats

step-by-step explanation:

an=a1+(n-1)(d)

a1 = 22   this is the first item in the sequence

d =6   this is how the sequence goes up

a)   an = 22 + (n-1) *6

b) a12 = 22 + (12-1) *6

    a12 = 22+11*6

  a12 = 22 +88

  a12 = 110

doubled

step-by-step explanation: