b = -4/9 X 27/12 + 16/8 X 5/-4 =
-4/9 * 27/12 + 16/8 * 5/-4
= -4*9*3/9*3*4 + 4*4*5/ 8*(-4)
= -4/4 + 80/-32
= -4* (-8)/4* (-8) + 80/ -32
= 32/-32 + 80/ -32
=32+80/-32
=112/-32
= -7*16/16*2
=-7/2
