Question 342207
Call the amount of gold in the first alloy x
Sixty grams of an alloy that contains less that 15% gold 
x <15% * 60
x <15/100 * 60 = 15/10 * 6 = 3/2 * 6 = 9
x<9grams

Call the amount of gold in the second alloy y
45 g of an alloy that is 20% gold
y < 20/100 * 40
y<8
the amount of gold in the resulting alloy is the sum of the 2 so it is
(x+y) <9 + 8 
(x+y)<17g

If you want to put this in percentage terms, we have a total weight of 60 + 45 = 105g
%gold <17/105 
%gold<16%