2.(30)

( 120)

3.( 1. 10.2.5)

( 1:2=5: 10)

(2.5)

( 10)4.(4)

(24)

(96)5.(3)(4 1)

( 1) ( 123) 6.( 120) 7.( 1)(x)(2)(√)(3)(x)(4)(√)(5)(√)8。 A quadrilateral with right angles must be a square. )9. 100=3+97

100= 1 1+89

100= 17+83

100=29+7 1

100=4 1+59

100=47+53

A: I can write six kinds.