Answer: 21. The two-digit number ab stands for 10a + b since the first digit represents 10s and the second represents units. If 10a + b = 7 (a + b), then 10a + b = 7a + 7b

lets see – the question is – notice that .9 equals 0.9 and .01 equals 0.01 – that makes it easier to keep straight Questions is – 4.7 + .9 + .01 . Take