There are 270 at colfax middle school, where the ratio of boys to girls is 5: 4. there are 180 students at winthrop middle school where the ratio of boys to girls is 4: 5. the two schools hold a dance and all students from both schools attend. what fraction of the students at the dance are girls? make sure to show all work.

Colfax:

Add the ratio numbers together:

5 + 4 = 9

Divide total students by that:

270 / 9 = 30

Multiply each ratio by 30:

Boys = 30 *5 = 150

Girls = 30 * 4 = 120

Do the same for Winthrop:

4 +5 = 9

180 /9 = 20

Boys = 20 * 4 = 80

Girls = 20 * 5 = 100

Total students = 270 + 180 = 450

Total Girls = 120 + 100 = 220

Fraction that are girls = 220 / 450 which reduces to 22/45

more detail

step-by-step explanation:

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