g.(-5/8)/( 8 3/4))←分数.带分数
construct △abc with ab=3cm,bc=2cm and ∠abc is right angle.
the length of a rectangle is 3cm lomger than its width.its perimerter is 42cm.find the length of the rectangle.
a retangle 36cm by 84cm is to be covered with squares which are of the same size.find the largest size of the squares that can be used to exactly cover the rectangle.
bell a is rung at 18-min interval,while bell b is rungat 27-min interval.if they rung together at 12:00 moon ,at what time will they be next rung together?