In a mixture of​ concrete, there are four lb of cement mix for each pound of gravel. if the mixture contains a total of 115 lb of these two​ ingredients, how many pounds of gravel are​ there

Respuesta :

For this case, the first thing we must do is define variables:
 x: pounds of gravel
 y: pounds of cement
 We now write the system of equations:
 x + y = 115
 y = 4x
 Solving the system of equations we have:
 x = 23
 y = 92
 Answer:
 
there are 23 pounds of gravel