53.49-(28.49+9.73)
=(53.49-28.49)-9.73
=25-(10-0.27)
=25-10+0.27
=15.27
1/ ( 7/13 × 7 + 6/13 × 7 )
=1/ ( (7/13+6/13) × 7 )
=1/7
7/8 - 14/15 + 1/8 - 1/15
=(7/8+1/8) - (14/15 + 1/15)
=1-1
=013分之7除7+13分之6乘7分之113分之7除7+13分之6乘7分之1 =7/13÷7+6/13x1/7 =(7/13)×(1/7)+(6/13)×(1/7) =(1/7)×(7/13+6/13) =(1/7)×1 =1/7