Also tính is from 倂. This is one of those "odd" times where the initial consonant mutates. Other such examples of Chinese b- mutating into Vietnamese t- are:
tỷ lệ (rate/ratio) = 比例 bi li
tiện lợi (advantageous) = 便利 bian li
You gotta add the tones, man... bǐlì (Cantonese bei2lai6) biànlì (Cantonese bin6lei6)
Also, that character is normally written 倂, pronounced bìng (Cantonese bing3/ping3), ‘put together, align’.
When translating this from vietnamese to english - I initially was confused if this was "they agree to buy the computer" vs "they agree with buying the computer". How would the second sentence translate into vietnamese?