Three-fifth of a number is equal to 70% of another number. What is the ratio between the first number and second number ?

$$\eqalign{ & {\text{Let}}\,{\text{the}}\,{\text{two}}\,{\text{numbers}}\,{\text{be}}\,X\,{\text{and}}\,Y \cr & {\text{According}}\,{\text{to}}\,{\text{question}}, \cr & X \times {\frac{3}{5}} = 70\% \,of\,Y \cr & \frac{{3X}}{5} = \frac{{70Y}}{{100}} \cr & \frac{X}{Y} = \frac{{ {70 \times 5} }}{{ {100 \times 3} }} = \frac{7}{6} \cr & X:Y = 7:6 \cr} $$