First exercise
To solve the first equation, multiply both sides by 6:
[tex] 6\cdot\dfrac{x}{6} = \dfrac{15}{36}\cdot 6 [/tex]
On the left hand side, the 6's simplify and we're left with [tex] x [/tex]
On the right hand side, we have
[tex] \dfrac{15}{36}\cdot 6 = \dfrac{15}{6} = \dfrac{5}{2}[/tex]
So, the answer is
[tex] x=\dfrac{5}{2} [/tex]
Second excercise
The unit rate means "how many miles she drives in a hour?" So, if we know how much she drove in 4.5 hours, if we divide by 4.5 we find out how much she drove in a single hour:
[tex] 300 \text{ miles in 4.5 hours} \iff \dfrac{300}{4.5} \text{ miles in 1 hour} [/tex]
Then, you can simplify
[tex] \dfrac{300}{4.5} = 66.\bar{6} [/tex]
