Question

Answer 1

y x 5 + y x 2 + y = 720 

=> y x ( 5+ 2 + 1 ) = 720 

=> y x 8 = 720

=> y = 720 : 8

=> y = 90

Answer 2

`y xx(5+2+1)=720`

`y xx 8 = 720`

`y=720:8`

`y=90`

Answer 3

y = 90

Answer 4

còn câu A

Answer 5

90