Ok so first I am assuming you ment 2 sevenths so 12 divided by 2 sevenths is 42. so the father is currently 42. so when she was 10 he was 40. since 10 is 4 times 40 that is the age we need. so 42 minus 40 is 2. therefore the answer is 2.
Yeah that’s the right answer
√2 is irrational
a rational number Q can be expressed in the form 
where a and b are integers.
- 18 = 
⇒ rational
⇒ rational
3.14 = 
⇒ rational
√2 = 1.414213562...... ⇒ irrational
The answer is A. if you divide 620 by four you would get 155 and the rest would have a decimal
