Answer:
852 students walking to school
Step-by-step explanation:
Lets start with a simple example so you can get it
if 60% of 100 students walk to school that means
60 students walk to school... right??
so lets simplify it more that means you have multiplied 100 (students) by 60%
or 
(note: you can say that 60% is equal to )
so the problem told 60% of 1420 students walk to school that means we should
do this: 
Given, the ratio of blocks A, B, C,D are in the ratio 4:7:3:1
Let us consider the common ratio to be ‘x’.
So, toy blocks with alphabet A is 4x and
toy blocks with alphabet B is 7x and
toy blocks with alphabet C is 3x and
toy blocks with alphabet D is x
Again, the number of ‘A’ blocks is 50 more than the number of ‘C’ blocks.
As no. of ‘A’ and ‘C’ blocks are 4x and 3x respectively.
So,
4x=50 + 3x
x=50
Thus, the number of ‘B’ blocks is 7x = 7(50) = 350
350 is the required number.
(10(1-(1/2)^5)/1-(1/2) =
20(1-1/32)
=155/8
