Andy has 31 coins made up of quarters and half dollars, and their total value is $11.00. how many quarters does he have?

4

Step-by-step explanation:

This situation has two unknowns - the total number of half dollars and the total number of quarters. Because we have two unknowns, we will write a system of equations with two equations using the two unknowns.

We write the first equation in terms of q by subtracting it across the equal sign to get h=31-q. We now substitute this for h in the second equation.

0.50(31-q)+0.25q=11

15.5-0.50q+0.25q=11

15.5-0.25q=11

After simplifying, we subtract 15.5 across and divide by the coefficient of q.

-0.25q=-4.5

q=4

We now know of the 31 coins that 4 are quarters.

yes. we do proportions in probabilities.

the answer is 48m^2!

step-by-step explanation: