Answer:
49
Step-by-step explanation:
the number is "ab" (2 digits).
ab - 10 = 3×(a+b)
a number is actually the sum of multiplying the digits with their associated powers of 10.
a×10 + b - 10 = 3a + 3b
7a - 2b = 10
b-1 = 2×a
b = 2a + 1
7a - 2×(2a+1) = 10
7a - 4a - 2 = 10
3a = 12
a = 4
b = 2×4 + 1 = 9
