Combined, Natalie and Ellie sold 90 boxes of Girl Scout cookies. If Natalie sold one-third of this, find the ratio of the boxes of cookies that Natalie sold to the number of boxes that Ellie sold.

they sold a total of 90 boxes

Natalie sold 1/3 of this......1/3 * 90 = 90/3 = 30....so Natalie sold 30.
that leaves (90 - 30) = 60.....Ellie sold 60

ratio of Natalie to Ellie is : 30/60 which reduces to 1/2.
so the ratio is : 1/2 or 1:2 or 1 to 2 <==