Question 7:
Define x :
Let the digit in the ones place be x.
The digit in the tens place is x+2.
The sum of the digit and its reverse is 66
Find x:
10(x + 2) + x + 10x + (x + 2) = 66
10x + 20 + x + 10x + x + 2 = 66
22x + 22 = 66
22x = 44
x = 2
Find the number:
The number in the ones place = x= 2
The number in the tens place = x = 2 + 2 = 4
Answer : The number is 42.
Question 8:
Define x:
Let the digit in the tens place be x.
The digit in the ones place is x+7.
The number = 10x + x + 7 = 11x + 7
If the digit interchange,
the number = 10(x + 7) + x = 10x + 70 + x = 11x + 70
Find x:
9(11x + 7) = 2(11x + 70)
99x + 63 = 22x + 140
99x - 22x = 140 - 63
77x = 77
x = 1
Find the number:
x = 1
x + 7 = 1 + 7 = 8
So the number is 18
Answer: The number is 18.