It takes 5 shovels of sand to make 1 shovel of mortar so how many will it take to have 30 shovels of mortar? You can put this in a proportion.
5/1 = x/30
You don't need to worry about the cement since it's asking for sand.
Cross multiply and you get x·1 and 30·5. So this means you need 150 shovels of sand. x=150 when you multiply 30·5.