Answer:
47
So the number in the unit digit is x since it is unknown.
the number in the tens digit is 3 less than x which can be expressed as x-3.
we have to multiply x-3 by 10 since x-3 is supposed to represent the digit in the tens place. so we have 10(x-3)+x (we are adding x because in any number we always add the tens digit by the ones, for example, 13, 10 + 3)
the reverse number would instead be x in the tens place and (x-3) in the ones place so the equation would be 10x+(x-3)
10(x-3)+x + 10x+(x-3) is equal to 121.
distribute 10(x-3), 10x-30
10x - 30 + x +`10x+x-3
Add like terms, 10x+x and -30-3
11x-33+11x
11x+11x = 22x
so we have 22x-33=121
add 33 to both sides to isolate 22x
121+33= 154
22x=154, divide both sides by 22
154/22 = 7
x=7 but this is only the ones digit.
10(x-3)+x is the equation, so replace x with 7
10(7-3)+7
7-3 = 4 and 4*10 = 40
40 + 7 = 47
original number is 47
