Question

a two digit no.is 3more than 4 times the sum of its digit if 18 idded to the no.are reversed .find the no

Answer 1

By mental calculations:
Reverse number by adding 18 means the digits differ by 2, 13,24,35, etc.
13/31 does not work, 4*4+3=19
24/42 does not work either, 6*4+3=27
35/53 4*(5+3)+3=35 works.
The pair of numbers would be 35 and 53.

By mathematics.
Let x and y be the two digits
10x+y=10y+x+18
9(x-y)=18
(x-y)=2 (as stated above)
Note: x>y or y>x, we don't know yet.

10x+y=4(x+y)+3
3y=6x-3
2x=y+1, so y>x, or y=x+2
Substitute y=x+2 in 2x=y+1
2x=x+2+1
x=3
y=5

as before

Answer 2

The expression for a two-digit no is 10x y..nd d digits ar x and y..xo in ur first statement:d no is 3 mre dan 4 timez d digtz xo..et is10x y=3 4(x y)..d eqn becomez 2x-y=1
in d 2nd statemnt.i cudn't gt u wel bt wt ah gt z dat wen18 is added to the digit,d no z reversd:18 10x y=10y x..d eqn becomez 2=y-x...xo solve d 2 eqns simultaneously,x=3 nd y equals 5..xo d orignal no z 35