D ) 13/20
1) Since Rachel drank 2/5 of the lemonade
Kurstyn: 1/4
They drank: 2/5 +1/4
2) To sum those fractions with different denominators let's calculate the LCM. Which is
We'll divide the LCM (20) by the 5 and multiply by each numerator and then sum
So Rachel and Kurstyn drank together 13/20 of the Lemonade Jar.