1. The problem says that the is ratio 1:3:5 by weight and Talil wants to make 180 kg of concrete mix.
 2. Therefore, you have:
 1+3+5=9
 180 kg/9=20 kg
 3. Each of the 9 parts of the ratio weights 20 kg. So, to make 180 kg of concrete mix, he needs:
 1x20 kg=20 kg of cement
 3x20 kg=60 kg of sand
 5x20 kg=100 kg of gravel
 4. Talil has:
 15kg of cement (Not enough)
 85kg of sand (More than enough)
 100kg of gravel (Enough)
 Does Talil have enough cement , sand and gravel to make concrete mix?
 The answer is: No, she does no have enough cement , sand and gravel to make concrete mix.