Question 464324
Let x the tenths, and y the ones. Base on the given data we write the system:

{{{system(y=2x, (10y+x)/2=(10x+y)-3)}}}, solve this system by substituting y=2x in

the second equation:{{{(10*2x+x)/2=10x+2x-3}}}, solving this linear equation we 

get:{{{21x/2=8x-3}}}<=>{{{21x-24x=-6}}}<=>{{{-3x=-6}}}<=>{{{x=2}}}, and 

{{{y=2x=2*2=4}}}. Thus, our number is 24.