Question

----- + ------ = 16
+ +
----- - ------- =12
26 16

Answer 1

Step-by-step

Let the empty boxes be a , b , c , d

a + b = 16 ---(1)

a + c = 26---(2)

b + d = 16---(3)

c - d = 12----(4)

On adding equation 3 and 4 , we get

b + c = 28----(5)

On subtracting equation 2 from 1 , we get

b - c = -10 ----(6)

On adding equation 5 and 6 , we get

2b = 18

=> b = 9

Now ,

c = 28 - 9 = 19

a = 16 - b = 16 -9 = 7

d = 16 - b = 16 -9 = 7

Answer 2

Please go to the attached picture..