Question

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

Answer 1

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