There are some red counters and some white counters in a bag. At the start, 7 of the counters are red, the rest of the counters are white
Alfie takes at random a counter from the bag.
He does not put the counter back in the
bag. omditional
Alfie then takes at random another counter from the bag.
21
The probability that the first counter Alfie takes is white and the second counter Alfie takes is red is 80
Work out the number of white counters in the bag at the start