Question

The value of a two digit number whose units digit is u and the sum of the digits is 7

write an algebraic expression

Answer 1

The expression is 70 - 9 u .

Explanation:

Digit at ones place = u

Let the digit at tens place is y.

Sum of the digits is 7.

y + u = 7

y = 7 - u

So, the number is

10 y + u

= 10 (7 - u) + u

= 70 - 10 u + u

= 70 - 9 u