let x and y be the two numbers respectively.
since there diff is 20 so
x-y=20....(1)
then they are in ratio 3:7 so
x/y=3/7
or x=3y/7....(2)
now putting the value of x in eqn (1) we get
3y/7-y=20
or 3y-7y=20×7
or -4y=140
or y=140/-4
y=-35
now keeping the value of y in eqn (2) we get
x=3×(-35)÷7
x=-15
therefore,the numbers are x=-15 and y=-35.