原式=24X21/45+51X19/43
=(24X21X43+51X19X45)/[(44+1)(44-1)]
=(21672+43605)/(1936-1)
=65277/1935
=7253/215
24乘45分之21+51乘43分之19等于（要用简便运算）
原式=24X21/45+51X19/43
=(24X21X43+51X19X45)/[(44+1)(44-1)]
=(21672+43605)/(1936-1)
=65277/1935
=7253/215