Answer:

Step-by-step explanation:
Given that,
A bricklayer needs to order 6300kg of building sand.
1 grain of this sand weighs
.
We need to find how many grains of sand are there in 6300 kg.
It can be just calculated as follows :
1 grain of sand = 

or
= 90000000 grans of sand
So, 6300 kg is equal to
.
Answer:
The angle of elevation is approximately 
Step-by-step explanation:
Notice that the two pieces of information given: "400 ft away from a building", and building that is "850 ft tall", can be regarded as the two legs of a right angle triangle (see attached image).
Then the angle
that we are trying to find (the angle of elevation) can be found by using the arc-tangent function:
