Let the two numbers be x and y.
Then their ratio, x/y = 3/5 ------ (1)
And their sum, x + y = 136 ------ (2)
cross-multiplying (1),
5x = 3y ---- (3)
and from (2),
x = 136 - y ----- (4)
substituting for (4) into (3),
5(136 - y) = 3y
680 - 5y = 3y
680 = 8y
y = 85
x = 136 - 85 = 51
Ans: x = 51, y = 85