BA can be another name for AB
Call the numbers x and y. According to the first sentence, x + y = 67. According to the second sentence, x = y + 5. You can combine these two equations to find the values of these variables:
x + y = 67
(y + 5) + y= 67
2y = 62
y = 31
You can use this to find x by plugging in y to either original equation:
x = y + 5
x = 31 + 5
x = 36
At noon, the temperature was 36 degrees. At midnight, the temperature was 30 degrees. By 6:00 am it drooped 5 degrees. Since it dropped 5 degrees, you subtract 5 from 30, which equals 25. It then increased by 11 degrees. Since the temperature increased, you add 11 to 25, which equals 36. At noon, the temperature was 36 degrees.