Partridge Company provides the following information for the year 2017:

Net income

$32,600

Market price of common shares

$2.00/share

Dividends paid - common shares

$0.10/share

Dividends paid - preferred shares

$1.00/share

Preferred shares outstanding at December 31, 2017

20,000 shares

Common shares outstanding at December 31, 2017

150,000 shares

Note: There were no new preferred shares issued in 2017; 60,000 common shares were issued on September 30, 2017.

73) Refer to Table 18-9. How much was the earnings per share for 2017?

A) $0.22

B) $0.30

C) $0.12

D) $0.08

Answer:C

Explanation:C) Weighted average common shares = 90,000 + (60,000 0.25) = 105,000

Calculations:($32,600 - $20,000)/105,000 shares = $0.12 per share My question is, why is answer C and i dont know how do you calculate weighted average number of common share outstand 105000?