4:2 and 2:1 are equivalent ratios to 8:4
Recall your d = rt, distance = rate * time
now, if say, by the time they meet, Mr Cunningham has travelled "d" miles, that means Mrs Cunningham must also had travelled "d" miles as well.
However, he left 3 hours earlier, so by the time he travelled "d" miles, and took say "t" hours, for her it took 3 hour less, because she started driving 3 hours later, so, she's been on the road 3 hours less than Mr Cunningham, so by the time they meet, Mrs Cunningham has travelled then "t - 3" hours.
Step-by-step explanation:
this is really complicated and tricky.
to create the next number, you have to add the first 2 digits of the previous number, then subtract the 3rd from the 2nd digit, multiply the 3rd and the 4th digit, and finally divide the 4th digit by the 5th.
so,
8+8 = 16
8-5 = 3
5×1 = 5
1/1 = 1
giving 16351 as next number.
the missing number we get then
1+6 = 7
6-3 = 3
3×5 = 15
5/1 = 5
giving 73155 as the next (missing) number.
control :
7+3 = 10
3-1 = 2
1×5 = 5
5/5 = 1
gives us 10251 as next number - correct.
but then it will end
1+0 = 1
0-2 = -2 ???? take the absolute value ?
2×5 = 10
5/1 = 5
U just add the exponents.
b^8 x b^4 = b^12
hope this helps :)