"is" means =
"%" means /100
"of" means *
"what number" means x
6 = 90/100 * x
6 * 100/90 = x
x = 600 / 90
x = 60 / 9
x = 20 / 3
x = 6 2/3
The problem is actually impossible- no solution- because there are 6 2/3 half dollars. Since we appear to be talking about coins, we can't have a fractional coin. The math works out that there are a total of 6 2/3 half dollars (Justin would have 2/3 of a half dollar), but since we can't have 2/3 of a coin. . .