Write the proper number in the box.(1) 7 + 8 = 10 + [ ](2) 7 + 8 = 20

1.	Write the proper number in the box.(1) 7 + 8 = 10 + [ ](2) 7 + 8 = 20 – [ ](3) 7 + 8 = 30 + [ ](4) 7 + 8 = 5 x [ ]
Answer» (1) 7 + 8 = 15 so, 10 + [ ] = 15. ∴ [ ] = 15 – 10 = 5 (2) 7 + 8 = 15 so, 20 – [ ] = 15. ∴ [ ] = 20 – 15 = 5 (3) 7 + 8 = 15 so, 30 + [ ] = 15. ∴ [ ] = 30 + 15 = 2 (4) 7 + 8 = 15 so, 5 x [ ] = 15. ∴[ ] = 15 + 5 = 3

Write the proper number in the box.(1) 7 + 8 = 10 + [ ](2) 7 + 8 = 20 – [ ](3) 7 + 8 = 30 + [ ](4) 7 + 8 = 5 x [ ]

Answer»

(1) 7 + 8 = 15 so, 10 + [ ] = 15.

∴ [ ] = 15 – 10 = 5

(2) 7 + 8 = 15 so, 20 – [ ] = 15.

∴ [ ] = 20 – 15 = 5

(3) 7 + 8 = 15 so, 30 + [ ] = 15.

∴ [ ] = 30 + 15 = 2

(4) 7 + 8 = 15 so, 5 x [ ] = 15.

∴[ ] = 15 + 5 = 3