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
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
