9jl9jk78j
设这箱灯泡共有x个,依题意得
x-168-(x-168)×(2/3)=(1/7)x
x-168-(2/3)x+112=(1/7)x
(1/3)x-56=(1/7)x
(1/3)x-(1/7)x=56
(4/21)x=56
x=56×(21/4)
x=294
答:这箱灯泡共有294个.
9jl9jk78j
设这箱灯泡共有x个,依题意得
x-168-(x-168)×(2/3)=(1/7)x
x-168-(2/3)x+112=(1/7)x
(1/3)x-56=(1/7)x
(1/3)x-(1/7)x=56
(4/21)x=56
x=56×(21/4)
x=294
答:这箱灯泡共有294个.