Given the task definition and input, reply with output. You are given a math word problem and you are supposed to apply multiple mathematical operators like addition, subtraction, multiplication, or division on the numbers embedded in the text to answer the following question and then only report the final numerical answer.

the treehouse is almost done ; all they need is to paint it . his father estimated that they will use 20 ounces of white paint 15 ounces of green paint and 34 ounces of brown paint . how many ounces of paint would they buy in total ?

69