c) 637 x 527 - 189=335510 / 526 x 637 + 448=335510
d) 677 x 874 + 251 =591949 / 678 x 874 - 623=591949
học tốt
c, 637x527-189/526x637+448=335918,116
d, 677x874+251/678x874-623=91398,5605
\(\frac{677\times874+251}{678\times874-623}\)
\(=\frac{677\times874+251}{677\times874+874-623}=\frac{677\times874+251}{677\times874+251}\)
\(=1\)