3. 3/4 * 2/5 - 3.6/25 * 5 /27
3.3/4*2/5-3.6/25*5/27=15/4*2/5-81/25*5/27=3/2*1/1-3/5*1/1=3/2-3/5=15-6/10=9/10
15/4*2/5-81/25*5/27=3/2-3/5=15/10-6/10=9/10