At a restaurant the ratio of kids meals sold to adult meals sold was 3:9. If there 12 kids meals sold, what is the combined amount of kids and adult meals sold?

have the unknown amount = x so 3x : 9x you know how many kids meals were bought is equal to the ratio (3x = 12, so x=4)you already know how many X's for the adults (9) so just multiply (9x4= 36)lastly add since you need to find the total meals bought (36+12= 48) 

[tex] \frac{3}{9} = \frac{12}{x}

3x = 108,
x = 36

36+12 = 48[/tex]