Answer:
Estimated Answer=
Exact Answer= 
Step-by-step explanation:
Steady speed of the object =10 and one tenth km/h = 
Distance to be Covered=4 and nine tenths km =
km
To the nearest integer,
Steady speed of the object = 10 km/hr
Distance=5km

=
The estimated answer is 1/2 hr.
Next, we determine the exact answer.

The exact time taken is 
Remember that you can do anything to an equation as long as you do it to both sides except divide by zero
so you can add like terms like this
you can add similar things like 1+3 and m+2m and m^2+2m^2 but not unlke things like 1+m or m+m^2
so m+2m=1m+2m=3m so
r-4+6r=3+8r
use commutative property to move numbers around (a+b=b+a)
group like terms
r+6r-4=3+8r
add like terms
1r+6r-4=3+8r
7r-4=3+8r
subtract 7r from both sides
7r-7r-4=3+8r-7r
0r-4=3+1r
-4=3+r
subtract 3 from both sides
-3-4=3-3+r
-7=0+r
-7=r
r=-7
I might be able to help you out
<12 would be A (51 degrees) because 2 and 10 are corresponding angles and there are 180 degrees on a straight line!
Hope this helps :)