a box has exactly 100 balls , and each ball is either red , blue , or white . if the box has 15 more blue balls than white balls , and thrice 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 15 more blue balls than white balls . . . equation # 2 : y = 15 + z . . . thrice as many red balls as blue balls . . . equation # 3 : x = 3 y solve equation # 2 for z : z = y - 15 now , we can replace both x and z with y in equation # 1 3 y + y + ( y - 15 ) = 100 5 y - 15 = 100 5 y = 115 y = 23 there are 23 blue balls . this is 15 more than the number of white balls , so z = 8 . that ' s the answer . just as a check , x = 69 , and 69 + 23 + 8 = 100 . answer = 8 , ( a )"
divide(subtract(100, multiply(15, const_3)), const_4)