8分之7x13分之2+13分之11x9分之7
=7/8×2/13+11/13×7/9
=7/13×2/8+7/13×11/9
=7/13×(2/8+11/9)
=7/13×53/36
=371/468
11-3分之2+11分之7
=11-2/3+7/11
=33/3-2/3+7/11
=31/3+7/11
=362/33
8分之7x13分之2+13分之11x9分之7
=7/8×2/13+11/13×7/9
=7/13×2/8+7/13×11/9
=7/13×(2/8+11/9)
=7/13×53/36
=371/468
11-3分之2+11分之7
=11-2/3+7/11
=33/3-2/3+7/11
=31/3+7/11
=362/33