You can easily solve this by setting up a proportion with walls on the top and paint on the bottom. First we can find the decimal equivalent of each of those fractions to make things easier. 5/8 = .625 and 4/5 = .8.
. What this is asking is "if 4/5 (.8) of a wall is covered by 5/8 (.625) of a gallon of paint, how many walls (x) will 1 gallon of paint cover?" If we cross multiply we have .625x = .8 and x = 1.28 which is the same as 1 7/25 walls/1 gallon, choice C.
Answer:
Step-by-step explanation:
Let the length and breadth of the rectangle be a,b units respectively.
Then the area will be ab square units.
Now if the length of the rectangle is reduced by 5 units and breadth is increased by 2 units then new length and breadth will be (a−5) units and (b+2) units.
Then new area will be (a−5)(b+2).
Then according to the problem,
(a−5)(b+2)−ab=−80
or, 2a−5b=−70.......(1).
Now if length of the rectangle is increased by 10 units and breadth is decreased by 5 units then new length and breadth will be (a+10) units and (b−5) units.
Then new area will be (a+10)(b−5).
Then according to the problem,
(a+10)(b−5)−ab=50
or, 10b−5a=100
or, 2b−a=20
or, 4b−2a=40......(2).
Now adding (1) and (2) we get
−b=−30
or, b=30.
Putting the value of b in (1) we get, a=40.
Now a+b=40+30=70.
Ok so,
20*2= 40
20*1/2=10
40+10=50
So Johncan travel 50 km in 2 1/2 hours.
Hope this helps :)
