2
Decrease R420 in the ratio 4:7​

Step-by-step explanation:

Let the numbers are 4x and 7x. According to the question if each number is increased by 20, the ratio becomes 7 : 9.

Then,

( 4x + 20 ) : ( 7x + 20 ) = 7 : 9

9( 4x + 20 ) = 7( 7x + 20 )

9( 4x ) + 9( 20 ) = 7( 7x ) + 7( 20 )

9( 20 ) - 7( 20 ) = 7( 7x ) - 9( 4x )

2( 20 ) = 49x - 36x

40 = 13 x

40 / 13 = x

Therefore, number are :–

4 x = 4( 40 / 13 ) = 160 / 13

7 x = 7( 40 / 13 ) = 280 / 13

this is not the answer this is just a question. is this middle school math?

step-by-step explanation:

step-by-step explanation:

if you want to solve percent error follow these steps.

1. subtract the accepted value from the experimental value.

2. take the absolute value of step 1.

3. divide that answer by the accepted value.

4. multiply that answer by 100 and add the % symbol to express the answer as a percentage.

if you want to solve percent of change just do this.

1. work out the difference (increase) between the two numbers you are comparing.

2. divide the increase by the original number and multiply the answer by 100. if your answer is a negative number then this is a percentage decrease.

hope this : )