Question

Guys help me please with this.

Answer 1

`\large\boxed{-(19)/(70)\to\boxed{19}}`

Explanation:

`(3)/(10)+-(4)/(7)=(3)/(10)-(4)/(7)\\\\\text{find the common denominator}\ LCD(10,\ 7)=70\\\\(3)/(10)=(3\cdot7)/(10\cdot7)=(21)/(70)\\\\(4)/(7)=(4\cdot10)/(7\cdot10)=(40)/(70)\\\\=(21)/(70)-(40)/(70)=(21-40)/(70)=-(19)/(70)`

Answer 2

`(3)/(10) + ( - (4)/(7) ) =`

`(3)/(10) - (4)/(7) =`

3 x 7 = 21

10 x 4 = 40

10 x 7 = 70

`= (21 - 40)/(70)`

`= ( - 19)/(70)`

`= - (19)/(70)`

So, the number that belongs in the green box is 19.