GIVING BRAINLIEST. Write a proportion that could be used to solve for each variable. Then solve. 12 balls in 2 boxes 78 balls in x boxes a. 12/2 = 78/x; x = 13 c. 12/2 = 78/x; x = 12 b. 2/12 = 78/x; x = 468 d. 12/2 = x/78; x = 458