x/ 1.2 >= 400/5
x & gt= 96
(2) Suppose he answers question X at least correctly.
x * 4-(25- 1-x)* 1 & gt; = 80
x & gt=20.8
He must get at least 2 1 correctly.
(3) Last year, the annual profit of the whole factory reached at least X million yuan.
x/240-(x- 100)/280 & gt; = 6000/ 10000 x & gt; = 308
(4) 10b+a & lt; 10a+b a & gt; b
10b+a & gt; 10a+b a & lt; b
10b +a = 10a +b a=b