If the ratio of white pens to green pens is 2 to 8 and there are a total of 30 pens, how many pens are white? explain. and show work

2 white pens: 8 green pens
add these together to get how many total pens you are talking about

2 white pens + 8 green pens = 10 pens total. 

However there are a total of 30 pens. 

30 ÷ 10 = 3
that means that there are 3 sets of 10 pens. 

2 white pens: 8 green pens
we can multiply the original ratio all by 3

3 x (2 white pens: 8 green pens)
6 white pens: 24 green pens 
add these together to get how many pens you are talking about
6 + 24 = 30 total pens. 

this means out of 30 total pens, 6 of them are white