Table:
0
A
B
C
D
E
1
Year ended March 31,
Period-to-period change
2
% Change 
2018
2017
Amount
% Change
3
(dollars in thousands)
4
Operating expenses:                
5
Research and development
$38,373
$22,593
$15,780
70%
6
Sales and marketing
121,246
96,154
25,092
26%
7
General and administrative
36,989
27,875
9,114
33%
8
Impairment of long-lived assets  
1,712
—
1,712
nm 
9
Restructuring  
832
—
832
nm 
10
Total operating expenses 
$199,152
$146,622
$52,530
36%

Questions and formulas:
Question: What was the average Research and development expenses in 2017 and 2018?
Formula: (B5 + C5) / 2
Formula2: (B5 + C5) / 2
Level: Calculation
Question: What was the average Sales and marketing expenses in 2017 and 2018?
Formula: (B6 + C6) / 2
Formula2: (B6 + C6) / 2
Level: Calculation