The ratio of the numbers A and B is four to seven. If the number A is increased by 20, how much will photography in the same proportion increase?

The ratio of the numbers A and B is four to seven. If the number A is increased by 20, how much will it increase than photography?

The topic is a bit difficult to understand. It would be easy to change "photography" to "B number".

The ratio of two numbers a and b = four to seven, so A/B =4/7, 7 A =4 B, A =4 B /7,

A number increases by 20 =(4 B /7)+20,

A number increases by 20/(B number +B number plus increment) =4/7.

B number plus increment = [A number increases by 20 /(4/7)]- B number = (A number increases by 20 *7/4)- B number = [(4 b/7)+20] * 7/4-B = B+20 * 7/4-B.

=20*7/4=5*7=35,

The above is the general method, and there is a simple method, that is, the incremental ratio is equal to the original ratio, and the result remains unchanged.

Just calculate the ratio of 20 to 4 to 7.

I hope it helps you.