5.设每箱有x个产品.
(8x+4)/5=(11x+1)/7+1
(8x+4)*7= (11x+1)*5+35
56x+28 = 55x+5+35
56x-55x=40-28
x =12
6.设经过x个小时后.
30+20x=90-10x
20x+10x=90-30
30x=60
x=2
车速:
30+20*2
=30+40
=70(千米/时)
5.设每箱有x个产品.
(8x+4)/5=(11x+1)/7+1
(8x+4)*7= (11x+1)*5+35
56x+28 = 55x+5+35
56x-55x=40-28
x =12
6.设经过x个小时后.
30+20x=90-10x
20x+10x=90-30
30x=60
x=2
车速:
30+20*2
=30+40
=70(千米/时)