Answer:
x+y= 21
0.10x+0.25y= 4.20
Step-by-step explanation:
You can write a system of equations that model the situation in which one equation would determine the number of coins by adding up all the coins she has and the other one would indicate the total amount Maria has by adding up the results of multiplying the value of each type of coin for the quantity:
x+y= 21
0.10x+0.25y= 4.20
x= amount of dimes
y= amount of quarters
