a box has exactly 100 balls , and each ball is either red , blue , or white . if the box has 12 more blue balls than white balls , and twice as many red balls as blue balls , how many white balls does the box has ?
x = the number of red balls y = the number of blue balls z = the number of white balls from the first sentence we have equation # 1 : x + y + z = 100 . . . the box has 12 more blue balls than white balls . . . equation # 2 : y = 12 + z . . . thrice as many red balls as blue balls . . . equation # 3 : x = 2 y solve equation # 2 for z : z = y - 12 now , we can replace both x and z with y in equation # 1 2 y + y + ( y - 12 ) = 100 4 y - 12 = 100 4 y = 112 y = 28 there are 28 blue balls . this is 15 more than the number of white balls , so z = 16 . that ' s the answer . just as a check , x = 56 , and 56 + 28 + 16 = 100 . answer = 16 , ( e )
divide(subtract(100, multiply(12, const_3)), const_4)