E條英文點解

1.If the two adjacent side of a square measure x cm and (2x-3)cm respectively, find the perimeter of the square.
（若正方形兩鄰邊分別量得 x cm 及 (2x - 3) cm，求正方形的周界。）

2x - 3 = 3
2x = 6
x = 3

Perimeter of the square
= (3 cm) x 4
= 12 cm


2.The cost of tea A is $30 per kg, the cost of tea B is $20 per kg. If w kg of tea A and (w+1) kg of tea B are mixed together, the cost of the mixed tea is $24 per kg. Find w.
（A 茶的成本每公斤 $30，B 茶的成本每公斤 $20。若把 w 公斤 A 茶與 (w+1) 公斤茶 B 混合，混合茶每公斤成本是 $24。計算 w。）

The total cost of the tea:
30w + 20(w + 1) = 24[w + (w + 1)]
30w + 20w + 20 = 48w + 24
2w = 4
w = 2