Question

In a two digit number units digit is 3 more than the tens digit .the no formed by interchanging the digits and the original no are in the ratio 7:4.Find the number???

Answer 1

Let the number be 10t+u
EQUATIONS:
u = t+3
(10u+t)/(10t+u) = 7/4
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Substitute to solve for t:
(10(t+3)+t)/(10t+(t+3)) = 7/4
(11t+30)/(11t+3) = 7/4

Cross multiply:
44t+120 = 77t+21
33t = 99
t = 3
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u=3+3 = 6 
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Number = 36