Using only addition what is 20 - 9 + 8 -7

In triangle abc, the length of side ab is 12 cm, the length of side bc is 5 cm, and the length of side ca is 9 cm. find the measure of angle a using the law of cosines.

Answer this question, only if you know the answer. 30 points and brainliest!

Acarton of juice contains 64 ounces miss wilson bought six cartons of juice how many ounces of juice did she buy