一題數學題目～幫幫我吧～！！

(a) 4500 is base salary, when he sells 50 watches he gets 1000 for commission, so he gets 1000/50=20 for each watch he sells.

20x+4500 = y


(b)
if x =320
20(320)+4500 = y
6400+4500 = y
10900 = y

2007-01-05 12:35:57 補充：
Philip的底薪係$4500，因為當佢賣到0隻錶時都有$4500薪金。當他賣50隻時有5500，100隻時有6500。(6500 - 5500)/(100隻 - 50隻) = 100/50隻 = 20/隻以上計到當philip賣到 一隻錶時有多少錢收入，所以他的月薪會是$4500 加 $20 乘佢賣了多少隻錶。x = Philip賣到多少隻錶y = Philip的月薪所以(a)的equation係20x 4500 = y

2007-01-05 12:39:05 補充：
以上補充條equation出唔到個加號，應該係咁20x 加 4500 = y(b) 如果 philip賣了320隻錶，薪金會是...只要將 320 sub番入 (a)的equation 就會計到

(a)y=$4500+$20x(each watch's price is $20)因為每個手錶的價錢是20元

(b)His income in last month
=$4500+$20*320
=$4500+$6400
=$10900
so his income was $10900 in last month

(a)y=20x+4500

(b)sub. x= 320 in the formula
y=20* 320 +4500
y=10900