(1)
÷2 5
×3 4
1 3
=
×8 15
1 3
=
8 45
答:这个数的
是1 3
.8 45
(2)设乙数是x
x-30=2409 14
x-30+30=240+309 14
x÷9 14
=270÷9 14
9 14
x=420
答:乙数是420.
(3)280÷(
+1)×3 4
3 4
=280÷
×7 4
3 4
=160×
3 4
=120(棵)
答:梨树有120棵.