5 is 25% of how many?

i.e. 25% of  y= 5

i.e. 25/100 × y = 5

i.e. y = 5 ×100/25

i.e. y = 100/5

i.e. y = 20

So, there are 20 teachers in a school.

Hope this has helped you to some extent. Now solve the other related problems with your friends.

1(1+1.8/4)x4

= 4( 1 + 0.45)

= 4 × 1.45

= 5.8

Hope this helped you to some extent. Now solve the other related problems with your friends.

By convention,

10 mm = 1cm

So, 1 mm = 1/10 cm

Hence, 537 mm = 537/10 cm = 53.7 cm

i.e. 537 mm = 53.7 cm

Hope this helped you to some extent.

Its true that "Any number [ except 0] raised to the power zero is 1"

Here is the explanation for you

Consider, 2 ^ 0 

= 2 ^ (1-1)   [ 1 -1 = 0]

 = 2^1 × 2^ ( -1)  [ Multiplication law of indices]

= 2^1/ 2^1 [ Division law of indices]

= 1

But for 0 ^ 0 

= = 0 ^ (1-1) [ 1 -1 = 0]

= 0^1 × 0^ ( -1) [ Multiplication law of indices]

= 0^1/ 0^1 [ Division law of indices]

= 0/0 [ indeterminate form]

= infinity [ value is undefined]

Hope this helped you to some extent. Now share the idea with your friends too.

By convention

1 m = 100 cm 

i.e. 1 m = 100 × 10 mm [ 1 cm = 10 mm]

So, 1 m = 1000 mm

Hence, 7 m = 7 × 1000 = 7000 mm

Hope this has helped you to some extent.

My dear friend here you are dealing with the "Simplification of Fractional numbers" So, the result will also be obtained in the fractional form [ or you can convert it into decimal numbers] but the result cannot be "Whole number". 

So, review your question.

2x^2-7x+5=0

i.e. 2x^2 - 2x - 5x +5 = 0 [ -2x -5x = -7x & their product is 10x^2]

i.e. 2x( x - 1) - 5( x -1) = 0

i.e. ( x -1)( 2x - 5) =0

i.e. x - 1 = 0 .............(i)

& 2x - 5 = 0..............(ii)

From equation (i)

x =1

From equation (ii)

x = 5/2

So, the required values of x are 1 or 5/2.

Hope this has helped you to some extent. Now solve the other related problems with your friends. 

By convention,

1 kg = 2.2 pounds [ Approximate value]

i.e. 1000 g = 2.2 pounds [ 1 kg = 1000 g]

i.e. 1 g = 2.2/1000 pounds 

So, 1 g = 0.0022 pounds

Hope this helped you to some extent.

By convention,

1000 kg  =  1 ton

3x+7-7y+2x-3y-1

= (3x +2x) + ( -7y -3y) + ( 7 - 1)  [ Grouping of like terms]

= 5x - 10y + 6

Hope this has helped you to some extent.