50%也就是0.5，（0.5+5）×10=0.5×10+5×10=5+50=55
50% = 50/100 = 1/2 = 0.5（50% + 5）× 10=（0.5 + 5）× 10= 5.5 × 10= 55
（0.5+5）×5=5.5×5=27.5
