The blank is 3.
What the question is assessing is the distributive property. The 3 term gets distributed to the 6 and the -2, which means it the 6 and the -2 are multiplied by 3.
Let the number be x
5 x = 8 + 3x
2 x = 8
x = 4 Ans
A plot where each data is split into a leaf usaully the last digit.