2.
Let x be the initial temperature.
When he measures the first time, the temperature dropped 5 degrees, becoming [tex]x-5[/tex]
When he measures the second time, the temperature dropped 5 more degrees, becoming [tex](x-5)-5=x-10[/tex]
When he measures the third time, the temperature dropped 5 more degrees, becoming [tex](x-10)-5=x-15[/tex]
So, we have
[tex]x-15=-7 \iff x=-7+15=8[/tex]
3.
We simply need to sum the fractions:
[tex]\dfrac{5}{6}+\dfrac{1}{12}+\dfrac{7}{8}[/tex]
In order to sum fractions, we must convert them to the same denominator. The LCM of 6, 12 and 8 is 24, and we have
[tex]\dfrac{5}{6}=\dfrac{5\cdot 4}{6\cdot 4}=\dfrac{20}{24}[/tex]
[tex]\dfrac{1}{12}=\dfrac{1\cdot 2}{12\cdot 2}=\dfrac{2}{24}[/tex]
[tex]\dfrac{7}{8}=\dfrac{7\cdot 3}{8\cdot 3}=\dfrac{21}{24}[/tex]
Now we can sum the fractions:
[tex]\dfrac{5}{6}+\dfrac{1}{12}+\dfrac{7}{8} = \dfrac{20}{24}+\dfrac{2}{24}+\dfrac{21}{24}=\dfrac{20+2+21}{24}=\dfrac{43}{24}[/tex]
To express this number in mixed fraction, we observe that
[tex]\dfrac{43}{24} = \dfrac{24+19}{24}=\dfrac{24}{24}+\dfrac{19}{24}=1\dfrac{19}{24}[/tex]
4.
Integers are numbers with no decimal digits (both positive and negative). Whole numbers are positive integers.
So, option F is wrong, because 1 and 2 are whole numbers.
Option G is wrong, because they are all whole numbers.
Option H is correct, because they are all integers but not whole numbers
Option J is wrong because 1/4 and 1/2 are not integers.
