Question

ratio between two numbers is 4:7.if each is increased by 20 ,than the ratio becomes 7:9, find the numbers.

Answer 1

let the numbers be 4x and 7x
so, (20+4x)/(20+7x)=7/9
(20+4x)9=7(20+7x)
180+36x=140+49x
40=13x
x=40/13

so, the numbers are
4x=4*(40/13)=160/13
7x=7*(40/13)=280/13

Answer 2

let no. be x

4x+20/7x+20 = 7/9                 (cross multiplying)

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

36x+180 = 49x+140

180-140 = 49x-36x
40 = 13x
x=40/13

so, the numbers are
4x=4*(40/13)=160/13
7x=7*(40/13)=280/13