1km = 1000m
1hr = 3600sec
Do proportions:
1km / 1000m = 15km / x
15000m = x
1hr = 3600sec
15000/3600 = 4.2m per second
Choice 4
7) Certainly there is a typo in the statement, just see that the expression of item (ii) is different from that of item (i). Probably the correct expression is:

. With this consideration, we can continue.
(i) Let E the expression that we are analyzing:

Since (x-1)² is a perfect square, it is a positive number. So, E is a result of a sum of two positive numbers, 2(x-1)² and 3. Hence, E is a positive number, too.
(ii) Manipulating the expression:

So, it's the case when E=0. However, E is always a positive number. Then, there is no real number x that satisfies the expression.
8) Let E the expression that we want to calculate:

Multiplying by (2-1) in the both sides:

Repeating the process, we obtain:
Answer:
answer is here
Step-by-step explanation:
https://www.mathpapa.com/algebra-calculator.html
7) answer-6t
t=toms cans collected
8) answer- 5.5
8.3-2.8=5.5
9) answer-14
56/4=14