Answer:
2x-7
Step-by-step explanation:
First distribute:
2x-12+5
Combine like terms:
-12+5=-7
Anwer:
2x-7
Answer:
The last answer 
Step-by-step explanation:

The formula to find it is 
so
is correct
The ratio is 4:3:1
let the ratio be 4x:3x:x
according to the question,4x+3x+x=40
8x=40
x=5
therefore amount of gravel=x*4=5*4=20

amount of sand=5*3=15

amount of cement=5*1=5