+ 10 is the missing step in the given chart.
Explanation:
Given data from the Flow chart,
Start = 20,
End = 6,
Second Step is ÷ 5.
Let us form the given information into two equations,
Consider the missing value as X.
20+X=Y ⇒1
Y÷5=6 ⇒2
where Y is the value of middle box.
From equation 1,
Y=6×5
Y=30.
From equation 2,
20+X=30.
X=30-20.
X= 10.
Thus + 10 is the missing step.