Four shovels of sand are used for every 5 shovels of gravel in making cement. how many shovels of gravel are needed for 64 shovels of sand?

For the answer to the question above,

4 shovels of sand are used for every 5 shovels of gravel

4s : 5g

How many shovels of gravel are needed for 64 shovels of sand?

64s : Xg

We need to calculate the value of X

4s : 5g

64s : Xg

4s. Xg = 5g. 64s

X = (5g*64s) / 4sg

= 5*64/4

= 5*16

= 80

80 shovels of gravel are needed.