Write missing tens or ones digit. 19 + ⎕1 = 60

The correct answer is: 4

To find partial sums add the digits in tens place and ones place seperately.
Since  The missing digit place value is tens digit add the digits in ones place first
Partial sum of  19 + ⎕1 = 60
Step 1 : Add digits in ones place seperately:
09
+ 01
___________
10
Her, 09 + 01 = 10 , the 1 in 10 is in tens place, it will get carried over to the tenths place.
Step 2 : Add digits in tens places
since 1 is carried over, the tens digit place becomes 20
20
+ _ _
_______
60
= 20 + x = 60
x = 60 -20
x = 40
Thus , the missing digit is 4,  19 + 41 = 60.